WO2025163460A2

WO2025163460A2 - Vaccines against respiratory diseases

Info

Publication number: WO2025163460A2
Application number: PCT/IB2025/050870
Authority: WO
Inventors: Ye Che; Bridget Yih Jiin HUANG; Kena Anne SWANSON
Original assignee: Pfizer Corp Belgium; Pfizer Corp SRL
Current assignee: Pfizer Corp Belgium; Pfizer Corp SRL
Priority date: 2024-01-30
Filing date: 2025-01-27
Publication date: 2025-08-07
Anticipated expiration: 2026-07-30
Also published as: WO2025163460A3

Abstract

The present disclosure relates to hMPV F protein mutants, nucleic acids or vectors encoding a hMPV F protein mutant, compositions comprising a hMPV F protein mutant or nucleic acid, and uses of the hMPV F protein mutants, nucleic acids or vectors, and compositions.

Description

PC073077A - 1 - VACCINES AGAINST RESPIRATORY DISEASES FIELD OF THE INVENTION The present invention relates to vaccines in general and vaccines against respiratory viruses such as hMPV A and B. BACKGROUND OF THE INVENTION Human paramyxoviruses and pneumoviruses are widespread pathogens, cause considerable disease burden, and include measles virus (MeV), mumps virus (MuV), respiratory syncytial virus (RSV), metapneumovirus (MPV), and parainfluenza virus types 1– 4 (PIV1–4). Human metapneumovirus (hMPV) is a respiratory virus that infects the lungs and breathing passages. HMPV is a clinically important respiratory viruses that result in substantial disease burden in children and account for significant pediatric hospitalization. There is near ubiquitous infection by the age of five and re-infections continue to be a burden throughout life (van den Hoogen et al., 2001). However, infants (6-12 months), the elderly, and immunocompromised populations are at an increased risk of hospitalization with more severe disease such as pneumonia and bronchiolitis (Deffrasnes et al., 2007). Despite the disease burden that hMPV presents, there are no vaccines or therapeutics that have been approved for prevention or treatment. hMPV is a member of the Pneumoviridae family, and its genome comprises three transmembrane surface glycoproteins: the attachment protein G, fusion protein F, and the small hydrophobic SH protein. There are two subtypes of hMPV, A and B. They differ primarily in the G glycoprotein, while the sequence of the F glycoprotein is more conserved between the two subtypes. The mature F glycoprotein has three general domains: ectodomain (ED), transmembrane domain (TM), and a cytoplasmic tail (CT). The F glycoprotein of hMPV is initially translated from the mRNA as a single 539-amino acid polypeptide precursor (referred to as “F0” or “F0 precursor”), which contains a signal peptide sequence (amino acids 1-18) at the N-terminus. Upon translation the signal peptide is removed by a signal peptidase in the endoplasmic reticulum. The remaining portion of the F0 precursor (i.e., residues 18-539) may be further cleaved at position 102/103 by cellular proteases to generate two linked fragments designated F1 (C-terminal portion; amino acids 103-539) and F2 (N-terminal portion; amino acids 19-102). F1 contains a hydrophobic fusion peptide at its N-terminus and two heptad-repeat regions (HRA and HRB). HRA is near the fusion peptide, and HRB is near the TM domain. The F1 and F2 fragments are linked together through two disulfide bonds. Either the uncleaved F0 protein without the signal peptide sequence or a F1-F2 heterodimer can form a hMPV F protomer. Three such protomers assemble to form the final hMPV F protein complex, which is a homotrimer of the three protomers. The F proteins of subtypes A and B are well conserved and an example sequence of the F0 precursor polypeptide for the A subtype is provided in SEQ ID NO: 1 (A2b strain (TN/95/3-54) GenBank GI: ACJ53569.1)), and for the B subtype is provided in SEQ ID NO: 7 (B2 strain (6073-B2) GenBank GI: QDA18370.1). SEQ ID NO:1 and SEQ ID NO:7 are both 539 amino acid sequences. The signal peptide sequence for SEQ ID NO:1 and SEQ ID NO:7 consists of amino acids 1-18. One of the primary antigens explored for hMPV subunit vaccines is the F protein. The hMPV F protein trimer mediates fusion between the virion membrane and the host cellular membrane and also promotes the formation of syncytia. In the virion prior to fusion with the membrane of the host cell, the largest population of F molecules forms a lollipop-shaped structure, with the TM domain anchored in the viral envelope. This conformation is referred to as the prefusion conformation. Prefusion hMPV A F is recognized for example by monoclonal antibodies (mAbs) MPE8, without discrimination between oligomeric states. During hMPV entry into cells, the F protein rearranges from the prefusion state (which may be referred to herein as “pre-F”), through an intermediate extended structure, to a post-fusion state (“post- F”). During this rearrangement, the C-terminal coiled-coil of the prefusion molecule dissociates into its three constituent strands, which then wrap around the globular head and join three additional helices to form the post-fusion six helix bundle. If a prefusion hMPV F trimer is subjected to increasingly harsh chemical or physical conditions, such as elevated temperature, it undergoes structural changes. Initially, there is loss of trimeric structure (at least locally within the molecule), and then rearrangement to the post-fusion form, and then denaturation of the domains. To prevent viral entry, F-specific neutralizing antibodies presumably must bind the prefusion conformation of F on the virion, or potentially the extended intermediate, before the viral envelope fuses with a cellular membrane. Thus, the prefusion form of the F protein is considered the preferred conformation as the desired vaccine antigen (Stewart Jones et al, PNAS 2021 Vol. 118 No. 39 and Hsieh et al, Nature Communications volume 13, Article number: 1299 (2022). However, the exact role of hMPV F prefusion form in eliciting immunogenicity is less established in comparison with RSV F. Upon extraction from a membrane with surfactants or expression as an ectodomain, physical or chemical stress, or storage, the F glycoprotein readily converts to the post-fusion form (Más et al, 2016 PLoS Pathog 12(9): e1005859). The preparation of hMPV prefusion F as a vaccine antigen has remained a challenge. Since the neutralizing and protective antibodies function by interfering with virus entry, it is postulated that an F antigen that elicits only post-fusion specific antibodies is not expected to be as effective as an F antigen that elicits prefusion specific antibodies. Therefore, it is considered more desirable to utilize an F vaccine that contains a F protein immunogen in the prefusion form. Efforts to date have not yielded an hMPV vaccine that has been demonstrated in the clinic to elicit sufficient levels of protection to support licensure of an hMPV vaccine. Therefore, there is a need for immunogens derived from a hMPV F protein that have improved properties, such as increased expression for example when recombinantly expressed in mammalian cells, enhanced immunogenicity, or improved stability of the prefusion form, as compared with the corresponding native hMPV F protein, as well as compositions comprising such an immunogen, such as a vaccine. SUMMARY OF THE INVENTION In some aspects, the present invention provides mutants of wild-type hMPV F proteins, wherein the mutants display introduced mutations in the amino acid sequence relative to the amino acid sequence of the corresponding wild-type hMPV F protein and are immunogenic against the wild-type hMPV F protein in the prefusion conformation or against a virus comprising the wild-type hMPV F protein. The amino acid mutations in the mutants include amino acid substitutions, deletions, or additions relative to a wild-type hMPV F protein. The present disclosure provides mutants of a wild-type hMPV F protein, wherein the introduced amino acid mutations are mutation of a pair of amino acid residues in a wild-type hMPV F protein to a pair of cysteines (”engineered interprotomer disulfide mutation”). The introduced pair of cysteine residues allows for formation of interprotomer disulfide bonds between the cysteine residues of different protomers of the trimer that stabilize the protein’s conformation or oligomeric state, such as the prefusion conformation and the trimeric structure. Examples of specific pairs of such mutations include 69C-Q195C, E80C-D224C, A211C-250C, 337C-423C and 111C-323C. In other embodiments, the present disclosure provides a mutant of a wild-type hMPV F protein, which mutant comprises a F1 polypeptide and a F2 polypeptide, wherein the mutant comprises at least one amino acid mutation relative to the amino acid sequence of the wild- type hMPV F protein, and wherein the amino acid mutation is an engineered interprotomer disulfide bond mutation selected from the group consisting of: (1) 69C and 195C; (2) 80C and 224C; (3) 211C and 250C; (4) 337C and 423C; and, (5) 111C and 323C. In other embodiments, the present disclosure provides a mutant of a wild-type hMPV F protein, which mutant comprises a F1 polypeptide and a F2 polypeptide, wherein the mutant comprises at least one amino acid mutation relative to the amino acid sequence of the wild- type hMPV F protein, and wherein the amino acid mutation is an engineered interprotomer disulfide bond mutation selected from the group consisting of: (1) T69C and Q195C; (2) E80C and D224C; (3) A211C and M250C; (4) T337C and T423C; and, (5) G111C and E323C. In other embodiments, the present disclosure provides hMPV F protein mutants, which comprise engineered interprotomer disulfide mutations selected from the group consisting of: (1) 69C and 195C; (2) 80C and 224C; (3) 211C and 250C; (4) 337C and 423C, (5) 111C and 323C; (6) 69C, 195C, 80C and 224C; (7) 69C, 195C, 211C and 250C; (8) 69C, 195C, 337C and 423C; (9) 69C, 195C, 111C and 323C; (10) 80C, 224C, 211C and 250C; (11) 80C, 224C, 337C and 423C; (12) 80C, 224C, 111C and 323C; (13) 211C, 250C, 337C and 423C; (14) 211C, 250C, 111C and 323C; (15) 337C, 423C, 111C and 323C; (16) 69C, 195C, 80C, 224C, 211C and 250C; (17) 69C, 195C, 80C, 224C, 337C and 423C; (18) 69C, 195C, 80C, 224C, 111C and 323C; (19) 69C, 195C, 211C, 250C, 337C and 423C; (20) 69C, 195C, 211C, 250C, 111C and 323C; (21) 69C, 195C, 337C, 423C, 111C and 323C; (22) 80C, 224C, 211C, 250C, 337C and 423C; (23) 80C, 224C, 211C, 250C, 111C and 323C; (24) 80C, 224C, 337C, 423C, 111C and 323C; and, (25) 211C, 250C, 337C, 423C, 111C and 323C. In other embodiments, the present disclosure provides hMPV F protein mutants, which comprise engineered interprotomer disulfide mutations selected from the group consisting of: (1) T69C and Q195C; (2) E80C and D224C; (3) A211C and M250C; (4) T337C and T423C, (5) G111C and E323C; (6) T69C, Q195C, E80C and D224C; (7) T69C, Q195C, A211C and M250C; (8) T69C, Q195C, T337C and T423C; (9) T69C, Q195C, G111C and E323C; (10) E80C, D224C, A211C and M250C; (11) E80C, D224C, T337C and T423C; (12) E80C, D224C, G111C and E323C; (13) A211C, M250C, T337C and T423C; (14) A211C, M250C, G111C and E323C; (15) T337C, T423C, G111C and E323C; (16) T69C, Q195C, E80C, D224C, A211C and M250C; (17) T69C, Q195C, E80C, D224C, T337C and T423C; (18) T69C, Q195C, E80C, D224C, G111C and E323C; (19) T69C, Q195C, A211C,M250C, T337C and T423C; (20) T69C, Q195C, A211C, M250C, G111C and E323C; (21) T69C, Q195C, T337C, T423C, G111C and E323C; (22) E80C, D224C, A211C, M250C, T337C and T423C; (23) E80C, D224C, A211C, M250C, G111C and E323C; (24) E80C, D224C, T337C, T423C, G111C and E323C; and, (25) A211C, M250C, T337C, T423C, G111C and E323C. In still other embodiments, the hMPV F protein mutants comprise one or more further amino acid mutations such as engineered disulfide mutations, cavity filling mutations, proline substitution mutations and/or glycine replacement mutations. In one embodiment, the hMPV F protein mutant is a mutant of a wild-type hMPV A F protein. In one embodiment, the hMPV F protein mutant is a mutant of a wild-type hMPV B F protein. In another aspect, the present invention provides a nucleic acid that encode a hMPV F protein mutant described herein. In a preferred embodiment, the nucleic acid is an RNA, more preferably an mRNA. In a preferred embodiment, the mRNA encodes a precursor F0 polypeptide that, when expressed in an appropriate cell, is processed into a full length hMPV F protein mutant disclosed herein (e.g. comprising one or more mutations, a F1 polypeptide comprising the ectodomain, the transmembrane domain and the cytoplasmic domain and a F2 polypeptide). In a preferred embodiment, the nucleic acid is an mRNA comprising a chemically modified nucleotide. In a preferred embodiment, the nucleic acid is an mRNA comprising a chemically modified nucleotide, preferably N1-methylpseudouridine. Preferably, all the uridines of the RNA are replaced by N1-methylpseudouridine. In another aspect, the invention provides immunogenic compositions that comprise a hMPV F protein mutant described in the disclosure, and/or (2) a nucleic acid, preferably mRNA, or a vector encoding such a hMPV F protein mutant described in the disclosure. In some embodiments, the Immunogenic composition comprises (1) a hMPV A F protein mutant described in the disclosure or a nucleic acid, preferably mRNA, encoding such mutant; (2) a hMPV B F protein mutant described in the disclosure or a nucleic acid, preferably mRNA, encoding such mutant; or, (3) a hMPV A F protein mutant described in the disclosure or a nucleic acid, preferably mRNA, encoding such mutant and a hMPV B F protein mutant described in the disclosure or a nucleic acid, preferably mRNA, encoding such mutant and optionally (4) a PIV1 F protein mutant or a nucleic acid, preferably mRNA, encoding such mutant; and/or (5) a PIV3 F protein mutant d or a nucleic acid, preferably mRNA, encoding such mutant; and/or (6) a RSV A F protein mutant d or a nucleic acid, preferably mRNA, encoding such mutant; and/or (7) a RSV B F protein mutant d or a nucleic acid, preferably mRNA, encoding such mutant. The present disclosure also relates to the use of a hMPV F protein mutant, nucleic acid encoding a hMPV F protein mutant, vector for expressing a hMPV F protein mutant, or composition comprising such protein mutant, nucleic acid or vector. In several embodiments, the present disclosure provides a method of eliciting an immune response to hMPV A and/or hMPV B in a subject, comprising administering to the subject an effective amount of a hMPV F protein mutant, a nucleic acid encoding a hMPV F protein mutant, or a composition comprising such protein mutant, nucleic acid or vector. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 provides a schematic representation of the hMPV precursor polypeptide F0 (1A) and a schematic representation of an mRNA encoding a hMPV F protein (1B). Figure 2 provides 50% neutralizing titers in PD2 mouse sera raised against different hMPV B F protein designs with 0.5 μg LNP-formulated modRNA. Dotted line represents the limit of detection at 20. DETAILED DESCRIPTION OF THE INVENTION A. DEFINITIONS As used herein, the singular forms "a," "an," and "the," refer to both the singular as well as plural, unless the context clearly indicates otherwise. For example, the term "an antigen" includes single or plural antigens and can be considered equivalent to the phrase "at least one antigen." The term “adjuvant” refers to a substance capable of enhancing, accelerating, or prolonging the body’s immune response to the antigen in a vaccine (although it is not the target antigen of the vaccine itself). An adjuvant may be included in the vaccine composition, or may be administered separately from the vaccine. The term “administration” refers to the introduction of a substance or composition into a subject by a chosen route. Administration can be local or systemic. For example, if the chosen route is intramuscular, the composition (such as a composition including a disclosed immunogen) is administered by introducing the composition into a muscle of the subject. The term “antigen” refers to a molecule that can be recognized by an antibody. Examples of antigens include polypeptides, peptides, lipids, polysaccharides, and nucleic acids containing antigenic determinants, such as those recognized by an immune cell. The term “conservative substitution” refers to the substitution of an amino acid with a chemically similar amino acid. Conservative amino acid substitutions providing functionally similar amino acids are well known in the art. The following six groups each contain amino acids that are conservative substitutions for one another: 1) alanine (A), serine (S), threonine (T); 2) aspartic acid (D), glutamic acid (E); 3) asparagine (N), glutamine (Q); 4) arginine (R), lysine (K); 5) isoleucine (I), leucine (L), methionine (M), valine (V); and 6) phenylalanine (F), tyrosine (Y), tryptophan (W). The term “degenerate variant” of a reference polynucleotide refers to a polynucleotide that differs in the nucleotide sequence from the reference polynucleotide but encodes the same polypeptide sequence as encoded by the reference polynucleotide. There are 20 natural amino acids, most of which are specified by more than one codon. For instance, the codons CGU, CGC, CGA, CGG, AGA, and AGG all encode the amino acid arginine. Thus, at every position where an arginine is specified within a protein encoding sequence, the codon can be altered to any of the corresponding codons described without altering the encoded protein. Because of the degeneracy of the genetic code, a large number of functionally identical nucleic acids encode any given polypeptide. The term “effective amount” refers to an amount of agent that is sufficient to generate a desired response. For instance, this can be the amount necessary to inhibit viral replication or to measurably alter outward symptoms of the viral infection. The term “epitope” (or “antigenic determinant” or “antigenic site”) refers to the region of an antigen to which an antibody, B cell receptor, or T cell receptor binds or responds. Epitopes can be formed from contiguous amino acids or noncontiguous amino acids juxtaposed by secondary, tertiary, or quaternary folding of a protein. Epitopes formed from contiguous amino acids are typically retained on exposure to denaturing solvents whereas epitopes formed by higher order folding are typically lost on treatment with denaturing solvents. The term “F0 polypeptide” (F0) when used in connection with hMPV F protein, refers to the precursor polypeptide of the hMPV F protein, which is composed of a signal polypeptide sequence, a F1 polypeptide sequence and a F2 polypeptide sequence. With rare exceptions the F0 polypeptides of the known hMPV strains consist of 539 amino acids. The term “F0 polypeptide” (F0) when used in connection with PIV1 F protein, refers to the precursor polypeptide of the PIV 1 F protein, which is composed of a signal polypeptide sequence, a F1 polypeptide sequence and a F2 polypeptide sequence. The term “F0 polypeptide” (F0) when used in connection with PIV3 F protein, refers to the precursor polypeptide of the PIV3 F protein, which is composed of a signal polypeptide sequence, a F1 polypeptide sequence and a F2 polypeptide sequence. The term “F1 polypeptide” (F1) when used in connection with hMPV F protein refers to a polypeptide chain of a mature hMPV F protein. Native F1 includes approximately residues 103-539 of the hMPV F0 precursor and is composed of from N- to C-terminus) an extracellular region (approximately residues 103-489), a transmembrane domain (approximately residues 490-514), and a cytoplasmic domain (also referred to as intracellular domain) (approximately residues 515-539). As used herein, the term encompasses both native F1 polypeptides and F1 polypeptides including modifications (e.g., amino acid substitutions, insertions, or deletion) from the native sequence, for example, modifications designed to stabilize a F mutant or to enhance the immunogenicity of a F mutant. The term “F1 polypeptide” (F1) when used in connection with PIV1 F protein refers to a polypeptide chain of a mature PIV1 F protein. Native F1 includes approximately residues 113-555 of the PIV1 F0 precursor and is composed of from N- to C-terminus) an extracellular region (approximately residues 103-496), a transmembrane domain (approximately residues 497-517), and a cytoplasmic domain (also referred to as intracellular domain) (approximately residues 518-555). As used herein, the term encompasses both native F1 polypeptides and F1 polypeptides including modifications (e.g., amino acid substitutions, insertions, or deletion) from the native sequence, for example, modifications designed to stabilize a F mutant or to enhance the immunogenicity of a F mutant. The term “F1 polypeptide” (F1) when used in connection with PIV3 protein refers to a polypeptide chain of a mature PIV3 F protein. Native F1 includes approximately residues 103- 539 of the PIV3 F0 precursor and is composed of from N- to C-terminus) an extracellular region (approximately residues 103-493), a transmembrane domain (approximately residues 494- 514), and a cytoplasmic domain (also referred to as intracellular domain) (approximately residues 515-539). As used herein, the term encompasses both native F1 polypeptides and F1 polypeptides including modifications (e.g., amino acid substitutions, insertions, or deletion) from the native sequence, for example, modifications designed to stabilize a F mutant or to enhance the immunogenicity of a F mutant. The term “F2 polypeptide” (F2) when used in connection with hMPV F protein refers to the polypeptide chain of a mature hMPV F protein. Native F2 includes approximately residues 19-102 of the hMPV F0 precursor. As used herein, the term encompasses both native F2 polypeptides and F2 polypeptides including modifications (e.g., amino acid substitutions, insertions, or deletion) from the native sequence, for example, modifications designed to stabilize a F mutant or to enhance the immunogenicity of a F mutant. In native hMPV F protein, the F2 polypeptide is linked to the F1 polypeptide by two disulfide bonds to form a F2-F1 heterodimer. The term “F2 polypeptide” (F2) when used in connection with PIV1 protein refers to the polypeptide chain of a mature PIV1 F protein. Native F2 includes approximately residues 22- 112 of the PIV1 F0 precursor. As used herein, the term encompasses both native F2 polypeptides and F2 polypeptides including modifications (e.g., amino acid substitutions, insertions, or deletion) from the native sequence, for example, modifications designed to stabilize a F mutant or to enhance the immunogenicity of a F mutant. In native PIV1 F protein, the F2 polypeptide is linked to the F1 polypeptide by two disulfide bonds to form a F2-F1 heterodimer. The term “F2 polypeptide” (F2) when used in connection with PIV3 F protein refers to the polypeptide chain of a mature PIV3 F protein. Native F2 includes approximately residues 19-109 of the PIV3 F0 precursor. As used herein, the term encompasses both native F2 polypeptides and F2 polypeptides including modifications (e.g., amino acid substitutions, insertions, or deletion) from the native sequence, for example, modifications designed to stabilize a F mutant or to enhance the immunogenicity of a F mutant. In native PIV3 F protein, the F2 polypeptide is linked to the F1 polypeptide by two disulfide bonds to form a F2-F1 heterodimer. The term “foldon” or “foldon domain” refers to an amino acid sequence that is capable of forming trimers. One example of such foldon domains is the peptide sequence derived from bacteriophage T4 fibritin, which has the sequence of GYIPEAPRDGQAYVRKDGEWVLLSTFL (SEQ ID NO:8). The term “mammal” refers to any animal species of the Mammalia class. Examples of mammals include: humans; non-human primates such as monkeys; laboratory animals such as rats, mice, guinea pigs; domestic animals such as cats, dogs, rabbits, cattle, sheep, goats, horses, and pigs; and captive wild animals such as lions, tigers, elephants, and the like. The term “glycoprotein” refers to a protein that contains oligosaccharide chains (glycans) covalently attached to polypeptide side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification known as glycosylation. The term “glycosylation site” refers to an amino acid sequence on the surface of a polypeptide, such as a protein, which accommodates the attachment of a glycan. An N-linked glycosylation site is triplet sequence of NX(S/T) in which N is asparagine, X is any residue except proline, and (S/T) is a serine or threonine residue. A glycan is a polysaccharide or oligosaccharide. Glycan may also be used to refer to the carbohydrate portion of a glycoconjugate, such as a glycoprotein, glycolipid, or a proteoglycan. The term “hMPV-2 mAb” refers to an hMPV F protein prefusion specific antibody which has a heavy chain variable domain comprising an amino acid sequence of SEQ ID NO:35 and a light chain variable domain comprising an amino acid sequence of SEQ ID NO:36. The term “host cells” refers to cells in which a vector can be propagated and its DNA or RNA expressed. The cell may be prokaryotic or eukaryotic. The term "identical" or percent "identity," in the context of two or more nucleic acid or polypeptide sequences, refers to two or more sequences or subsequences that are the same or have a specified percentage of amino acid residues or nucleotides that are the same, when compared and aligned for maximum correspondence. Methods of alignment of sequences for comparison are well known in the art. Once aligned, the number of matches is determined by counting the number of positions where an identical nucleotide or amino acid residue is present in both sequences. The percent sequence identity is determined by dividing the number of matches either by the length of the sequence set forth in the identified sequence, or by an articulated length (such as 100 consecutive nucleotides or amino acid residues from a sequence set forth in an identified sequence), followed by multiplying the resulting value by 100. For example, a peptide sequence that has 1166 matches when aligned with a test sequence having 1554 amino acids is 75.0 percent identical to the test sequence (1166÷1554*100=75.0). Optimal alignment of sequences for comparison can be conducted, e.g., by the local homology algorithm of Smith and Waterman, Adv. Appl. Math.2:482, 1981, by the homology alignment algorithm of Needleman and Wunsch, Mol. Biol. 48:443, 1970, by the search for similarity method of Pearson and Lipman, Proc. Nat'l. Acad. Sci. USA 85:2444, 1988, by computerized implementations of these algorithms (GAP, BESTFIT, FASTA, and TFASTA in the Wisconsin Genetics Software Package, Genetics Computer Group, 575 Science Dr., Madison, WI), or by manual alignment and visual inspection (see, e.g., Sambrook et al. (Molecular Cloning: A Laboratory Manual, 4th ed, Cold Spring Harbor, New York, 2012) and Ausubel et al. (In Current Protocols in Molecular Biology, John Wiley and Sons, New York, through supplement 104, 2013). The term “immunogenic” refers to the ability of a substance to cause, elicit, stimulate, or induce an immune response against a particular antigen, in an animal, whether in the presence or absence of an adjuvant. The term "immune response" refers to any detectable response of a cell or cells of the immune system of a host mammal to a stimulus (such as an immunogen), including, but not limited to, innate immune responses (e.g., activation of Toll receptor signaling cascade), cell- mediated immune responses (e.g., responses mediated by T cells, such as antigen-specific T cells, and non-specific cells of the immune system), and humoral immune responses (e.g., responses mediated by B cells, such as generation and secretion of antibodies into the plasma, lymph, and/or tissue fluids). Examples of immune responses include an alteration (e.g., increase) in Toll-like receptor activation, lymphokine (e.g., cytokine (e.g., Th1, Th2 or Th17 type cytokines) or chemokine) expression or secretion, macrophage activation, dendritic cell activation, T cell (e.g., CD4+ or CD8+ T cell) activation, NK cell activation, B cell activation (e.g., antibody generation and/or secretion), binding of an immunogen (e.g., antigen (e.g., immunogenic polypeptide)) to an MHC molecule, induction of a cytotoxic T lymphocyte ("CTL") response, induction of a B cell response (e.g., antibody production), and, expansion (e.g., growth of a population of cells) of cells of the immune system (e.g., T cells and B cells), and increased processing and presentation of antigen by antigen presenting cells. The term “immune response” also encompasses any detectable response to a particular substance (such as an antigen or immunogen) by one or more components of the immune system of a vertebrate animal in vitro. The term “immunogen” refers to a compound, composition, or substance that is immunogenic as defined herein below. The term ‘immunogenic composition” refers to a composition comprising an immunogen. The term “MPE8” refers to an antibody described in Corti et al. [Corti, D., Bianchi, S., Vanzetta, F., Minola, A., Perez, L., Agatic, G., Lanzavecchia, A. Cross-neutralization of four paramyxoviruses by a human monoclonal antibody. Nature, 501(7467), 439-443 (2013)], which has a heavy chain variable domain comprising an amino acid sequence of SEQ ID NO:33 and a light chain variable domain comprising an amino acid sequence of SEQ ID NO:34. The term “mutant” of a wild-type hMPV F protein, “mutant” of a hMPV F protein, “hMPV F protein mutant,” or “modified hMPV F protein” refers to a polypeptide that displays introduced mutations relative to a wild-type F protein and is immunogenic against the wild-type F protein. The term “mutant” of a wild-type PIV1 F protein, “mutant” of a PIV1 F protein, “PIV1 F protein mutant,” or “modified PIV1 F protein” refers to a polypeptide that displays introduced mutations relative to a wild-type F protein and is immunogenic against the wild-type F protein. The term “mutant” of a wild-type PIV3 F protein, “mutant” of a PIV3 F protein, “PIV3 F protein mutant,” or “modified PIV3 F protein” refers to a polypeptide that displays introduced mutations relative to a wild-type F protein and is immunogenic against the wild-type F protein. The term “mutation” refers to deletion, addition, or substitution of amino acid residues in the amino acid sequence of a protein or polypeptide as compared to the amino acid sequence of a reference protein or polypeptide. Throughout the specification and claims, the substitution of an amino acid at one particular location in the protein sequence is referred to using a notation "(amino acid residue in wild type protein)(amino acid position)(amino acid residue in engineered protein)". For example, a notation Y75A refers to a substitution of a tyrosine (Y) residue at the 75th position of the amino acid sequence of the reference protein by an alanine (A) residue (in a mutant of the reference protein). In cases where there is variation in the amino acid residue at the same position among different wild-type sequences, the amino acid code preceding the position number may be omitted in the notation, such as “75A.” The term “native” or “wild-type” protein, sequence, or polypeptide refers to a naturally existing protein, sequence, or polypeptide that has not been artificially modified by selective mutations. The term “pharmaceutically acceptable carriers” refers to a material or composition which, when combined with an active ingredient, is compatible with the active ingredient and does not cause toxic or otherwise unwanted reactions when administered to a subject, particularly a mammal. Examples of pharmaceutically acceptable carriers include solvents, surfactants, suspending agents, buffering agents, lubricating agents, emulsifiers, absorbents, dispersion media, coatings, and stabilizers. The term “prefusion-specific antibody” refers to an antibody that specifically binds to the F glycoprotein in a prefusion conformation, but does not bind to the F protein in a post- fusion conformation. Exemplary prefusion-specific antibodies include the MPE8 and hMPV-2 mAbs. The term “prime-boost vaccination” refers to an immunotherapy regimen that includes administration of a first immunogenic composition (the primer vaccine) followed by administration of a second immunogenic composition (the booster vaccine) to a subject to induce an immune response. The primer vaccine and the booster vaccine typically contain the same immunogen and are presented in the same or similar format. However, they may also be presented in different formats, for example one in the form of a vector and the other in the form of a naked DNA plasmid. The skilled artisan will understand a suitable time interval between administration of the primer vaccine and the booster vaccine. Further, the primer vaccine, the booster vaccine, or both primer vaccine and the booster vaccine additionally include an adjuvant. The term “prefusion conformation” refers to a structural conformation adopted by an F protein or mutant that can be specifically bound by a prefusion specific antibody such as for example MPE8 mAb for hMPV A and hMPV-2 mAb for hMPV B. The term “post-fusion conformation” refers to a structural conformation adopted by the F protein that is not specifically bound a by prefusion-specific antibody MPE8 mAb or hMPV- 2 mAb. Native F protein adopts the post-fusion conformation subsequent to the fusion of the virus envelope with the host cellular membrane. F protein may also assume the post-fusion conformation outside the context of a fusion event, for example, under stress conditions such as heat and low osmolality, when extracted from a membrane, when expressed as an ectodomain, or upon storage. The term “soluble protein” refers to a protein capable of dissolving in aqueous liquid and remaining dissolved. The solubility of a protein may change depending on the concentration of the protein in the water-based liquid, the buffering condition of the liquid, the concentration of other solutes in the liquid, for example salt and protein concentrations, and the temperature of the liquid. The term “specifically bind,” in the context of the binding of an antibody to a given target molecule, refers to the binding of the antibody with the target molecule with higher affinity than its binding with other tested substances. For example, an antibody that specifically binds to the hMPV F protein in prefusion conformation is an antibody that binds hMPV F protein in prefusion conformation with higher affinity than it binds to the hMPV F protein in the post-fusion conformation. The term “therapeutically effective amount” refers to the amount of agent that is sufficient to prevent, treat (including prophylaxis), reduce and/or ameliorate the symptoms and/or underlying causes of a disorder. The term “vaccine” refers to a pharmaceutical composition comprising an immunogen that is capable of eliciting a prophylactic or therapeutic immune response in a subject. Typically, a vaccine elicits an antigen- specific immune response to an antigen of a pathogen, for example a viral pathogen. The term “vector” refers to a nucleic acid molecule capable of transporting or transferring a foreign nucleic acid molecule. The term encompasses both expression vectors and transcription vectors. The term “expression vector” refers to a vector capable of expressing the insert in the target cell, and generally contains control sequences, such as enhancer, promoter, and terminator sequences, that drive expression of the insert. The term “transcription vector” refers to a vector capable of being transcribed but not translated. Transcription vectors are used to amplify their insert. The foreign nucleic acid molecule is referred to as “insert” or “transgene.” A vector generally consists of an insert and a larger sequence that serves as the backbone of the vector. Based on the structure or origin of vectors, major types of vectors include plasmid vectors, cosmid vectors, phage vectors such as lambda phage, viral vectors such as adenovirus (Ad) vectors, and artificial chromosomes. B. HMPV MUTANTS The present disclosure relates to hMPV F protein mutants, immunogenic compositions comprising the hMPV F protein mutants, methods for producing the hMPV F protein mutants, compositions comprising the hMPV F protein mutants, and nucleic acids that encode the hMPV F protein mutants. 1. EXEMPLARY EMBODIMENTS (E) OF THE INVENTION Exemplary embodiments (E) of the invention provided herein include: E1. A mutant of a wild-type hMPV F protein, which mutant comprises a F1 polypeptide and a F2 polypeptide, wherein the mutant comprises at least one amino acid mutation relative to the amino acid sequence of the wild-type hMPV F protein, and wherein the amino acid mutation is an engineered interprotomer disulfide mutation selected from the group consisting of (1) 69C and 195C; (2) 80C and 224C; (3) 211C and 250C; (4) 337C and 423C; and, (5) 111C and 323C. E2. The mutant according to E1 wherein the engineered interprotomer disulfide mutation is selected from the group consisting of (1) T69C and Q195C; (2) E80C and D224C; (3) A211C and M250C; (4) T337C and T423C; and, (5) G111C and E323C. E3. The mutant according to E1 or E2 wherein the mutant comprises two engineered interprotomer disulfide mutations selected from the group consisting of (1) T69C and Q195C; (2) E80C and D224C; (3) A211C and M250C; (4) T337C and T423C; and, (5) G111C and E323C. E4. The mutant according to E1 or E2 wherein the mutant comprises three engineered interprotomer disulfide mutations selected from the group consisting of (1) T69C and Q195C; (2) E80C and D224C; (3) A211C and M250C; (4) T337C and T423C; and, (5) G111C and E323C. E5. The mutant according to E1 or E2 wherein the mutant comprises engineered interprotomer disulfide mutations selected from the group consisting of: (1) 69C and 195C; (2) 80C and 224C; (3) 211C and 250C; (4) 337C and 423C, (5) 111C and 323C; (6) 69C, 195C, 80C and 224C; (7) 69C, 195C, 211C and 250C; (8) 69C, 195C, 337C and 423C; (9) 69C, 195C, 111C and 323C; (10) 80C, 224C, 211C and 250C; (11) 80C, 224C, 337C and 423C; (12) 80C, 224C, 111C and 323C; (13) 211C, 250C, 337C and 423C; (14) 211C, 250C, 111C and 323C; (15) 337C, 423C, 111C and 323C; (16) 69C, 195C, 80C, 224C, 211C and 250C; (17) 69C, 195C, 80C, 224C, 337C and 423C; (18) 69C, 195C, 80C, 224C, 111C and 323C; (19) 69C, 195C, 211C, 250C, 337C and 423C; (20) 69C, 195C, 211C, 250C, 111C and 323C; (21) 69C, 195C, 337C, 423C, 111C and 323C; (22) 80C, 224C, 211C, 250C, 337C and 423C; (23) 80C, 224C, 211C, 250C, 111C and 323C; (24) 80C, 224C, 337C, 423C, 111C and 323C; and, (25) 211C, 250C, 337C, 423C, 111C and 323C. E6. The mutant according to E1 or E2 wherein the mutant comprises engineered interprotomer disulfide mutations selected from the group consisting of: (1) T69C and Q195C; (2) E80C and D224C; (3) A211C and M250C; (4) T337C and T423C, (5) G111C and E323C; (6) T69C, Q195C, E80C and D224C; (7) T69C, Q195C, A211C and M250C; (8) T69C, Q195C, T337C and T423C; (9) T69C, Q195C, G111C and E323C; (10) E80C, D224C, A211C and M250C; (11) E80C, D224C, T337C and T423C; (12) E80C, D224C, G111C and E323C; (13) A211C, M250C, T337C and T423C; (14) A211C, M250C, G111C and E323C; (15) T337C, T423C, G111C and E323C; (16) T69C, Q195C, E80C, D224C, A211C and M250C; (17) T69C, Q195C, E80C, D224C, T337C and T423C; (18) T69C, Q195C, E80C, D224C, G111C and E323C; (19) T69C, Q195C, A211C,M250C, T337C and T423C; (20) T69C, Q195C, A211C, M250C, G111C and E323C; (21) T69C, Q195C, T337C, T423C, G111C and E323C; (22) E80C, D224C, A211C, M250C, T337C and T423C; (23) E80C, D224C, A211C, M250C, G111C and E323C; (24) E80C, D224C, T337C, T423C, G111C and E323C; and, (25) A211C, M250C, T337C, T423C, G111C and E323C. E7. The mutant according to any one of E1 to E6 comprising one or more further engineered disulfide mutation selected from the group consisting of G366C and D454C, T411C and Q434C, I137C and A159C, A140C and S149C, L141C and A159C, L141C and A161C, E146C and T160C, V148C and L158C and T150C and R156C. E8. The mutant according to any one of E1 to E7, wherein the mutant comprises one or more, preferably one, two or three cavity filling mutations. E9. The mutant according to E8, wherein the mutant comprises one or more, preferably one, two or three, cavity filling mutations selected from group consisting of T49I, S149T, A159V, S291I, T365I and L473F. E10. The mutant according to any one of E1 to E9, wherein the mutant comprises a proline substitution mutation. E11. The mutant according to E10, wherein the mutant comprises one or more, preferably one, proline substitution mutation selected from the group consisting of L66P, L110P, S132P, N145P, L187P, V449P and A459P. E12. The mutant according to any one of E1 to E11, wherein the mutant comprises a glycine replacement mutation. E13. The mutant according to E12, wherein the mutant comprises one or more, preferably one, glycine replacement mutation selected from the group consisting of G106A, G121A and G239A. E14. The mutant according to any one of E1 to E13 wherein the mutant comprises the mutations Q100R and S101R. E15. The mutant according to E1 wherein (a) the mutant comprises a cysteine (C) at position 69 (69C) and at position 195 (195C), and wherein the mutant comprises a F1 polypeptide and a F2 polypeptide selected from the group consisting of: (1) a F2 polypeptide comprising the amino acid sequence of SEQ ID NO:10 and a F1 polypeptide comprising the amino acid sequence of SEQ ID NO:9; (2) a F2 polypeptide comprising an amino acid sequence that is at least 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:10 and a F1 polypeptide comprising an amino acid sequence that is at least 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:9 or; (b) the mutant comprises a cysteine (C) at position 80 (80C) and at position 224 (224C), and wherein the mutant comprises a F1 polypeptide and a F2 polypeptide selected from the group consisting of: (1) a F2 polypeptide comprising the amino acid sequence of SEQ ID NO:12 and a F1 polypeptide comprising the amino acid sequence of SEQ ID NO:11; (2) a F2 polypeptide comprising an amino acid sequence that is at least 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:12 and a F1 polypeptide comprising an amino acid sequence that is at least 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:11 or; (c) the mutant comprises a cysteine (C) at position 211 (211C) and at position 250 (250C), and wherein the mutant comprises a F1 polypeptide and a F2 polypeptide selected from the group consisting of: (1) a F2 polypeptide comprising the amino acid sequence of SEQ ID NO:14 and a F1 polypeptide comprising the amino acid sequence of SEQ ID NO:13; (2) a F2 polypeptide comprising an amino acid sequence that is at least 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:14 and a F1 polypeptide comprising an amino acid sequence that is at least 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:13 or; (d) the mutant comprises a cysteine (C) at position 337 (337C) and at position 423 (423C), and wherein the mutant comprises a F1 polypeptide and a F2 polypeptide selected from the group consisting of: (1) a F2 polypeptide comprising the amino acid sequence of SEQ ID NO:16 and a F1 polypeptide comprising the amino acid sequence of SEQ ID NO:15; (2) a F2 polypeptide comprising an amino acid sequence that is at least 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:16 and a F1 polypeptide comprising an amino acid sequence that is at least 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:15 or; (e) the mutant comprises a cysteine (C) at position 111 (111C) and at position 323 (323C), and wherein the mutant comprises a F1 polypeptide and a F2 polypeptide selected from the group consisting of: (1) a F2 polypeptide comprising the amino acid sequence of SEQ ID NO:18 and a F1 polypeptide comprising the amino acid sequence of SEQ ID NO:17; (2) a F2 polypeptide comprising an amino acid sequence that is at least 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:18 and a F1 polypeptide comprising an amino acid sequence that is at least 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:17. E16. The mutant according to any one of E1 to E15, wherein the F1 polypeptide lacks the entire cytoplasmic domain. E17. The mutant according to any one of E1 to E16, wherein the F1 polypeptide lacks the cytoplasmic domain and a portion of or all entire transmembrane domain. Preferably, the F1 polypeptide lacks the cytoplasmic domain and the transmembrane domain. E18. The mutant according to any one of E1 to E15, wherein the F1 polypeptide comprises the ectodomain, the transmembrane domain and the cytoplasmic domain. In a preferred embodiment, the mutant comprises the full length F1 polypeptide and the full length F2 polypeptide. E19. The mutant according to any one of E1 to E18, wherein the mutant is linked to a trimerization domain. Preferably, the trimerization domain is a GCN4 leucine zipper or a phage T4 fibritin foldon. E20. The mutant according to E19, wherein the trimerization domain is a phage T4 fibritin foldon. E21. The mutant according to E20, wherein the trimerization domain is a phage T4 fibritin foldon of SEQ ID NO.8. E22. The mutant according to any one of E19 to E21, wherein the trimerization domain is linked to the C-terminus of the F1 polypeptide. E23. The mutant according to E22, wherein the trimerization domain is linked to the C-terminus of the F1 polypeptide via a linker. E24. The mutant according to E23, wherein the trimerization domain is linked to the C-terminus of the F1 polypeptide via a linker selected from the group consisting of GG, GS, GGGS or SAIG. E25. The mutant according to E24, wherein the linker is GGGS. E26. The mutant according to any one of E1 to E25, wherein the mutant is in the form of a trimer. E27. The mutant according to any one of E1 to E26, wherein the mutant is in the prefusion conformation. E28. The mutant according to any one of E1 to E27, wherein the mutant is in the prefusion conformation and specifically binds to an antibody specific for the hMPV F ectodomain in the prefusion, but not postfusion, conformation (such as MPE8 mAb or hMPV-2 mAb). E29. The mutant according to any one of E1 to E28, wherein the mutant is in the prefusion conformation and specifically binds to MPE8 mAb or hMPV-2 mAb as measured by ELISA, preferably as disclosed in the Examples. E30. The mutant according to any one of E1 to E29, which has increased stability as compared with the corresponding wild-type hMPV F protein, wherein the stability is measured by binding of the mutant with antibody MPE8 or hMPV-2. E31. The mutant of any one of E1 to E30 wherein the wild-type hMPV F protein is SEQ ID NO:1. E32. The mutant of any one of E1 to E30 wherein the wild-type hMPV F protein is SEQ ID NO:2. E33. The mutant of any one of E1 to E30 wherein the wild-type hMPV F protein is SEQ ID NO:3. E34. The mutant of any one of E1 to E30 wherein the wild-type hMPV F protein is SEQ ID NO:4. E35. The mutant of any one of E1 to E30 wherein the wild-type hMPV F protein is SEQ ID NO:5. E36. The mutant of any one of E1 to E30 wherein the wild-type hMPV F protein is SEQ ID NO:6. E37. The mutant of any one of E1 to E30 wherein the wild-type hMPV F protein is SEQ ID NO:7. E38. The mutant of any one of E1 to E30 wherein the wild-type hMPV is of subtype A. E39. The mutant of any one of E1 to E30 wherein the wild-type hMPV is of subtype B. E40. The mutant of any one of E1 to E30 wherein the amino acid positions correspond to the amino acid sequence of a reference of SEQ ID NO:1. E41. The mutant of any one of E1 to E30 wherein the amino acid positions correspond to the amino acid sequence of a reference of SEQ ID NO:7. E42. A nucleic acid comprising at least one coding sequence encoding at least one mutant of a wild-type hMPV F protein according to any one of embodiments E1-E41, preferably E18, or an immunogenic fragment or immunogenic variant thereof, wherein the nucleic acid comprises at least one heterologous untranslated region (UTR). E43. A nucleic acid according to any one of the preceding embodiments, wherein the at least one heterologous untranslated region is selected from at least one heterologous 5’-UTR and/or at least one heterologous 3’-UTR. E44. A nucleic acid according to any one of the preceding embodiments, wherein the at least one heterologous 3’-UTR comprises or consists of a nucleic acid sequence having at least, at most, exactly, or between any two of 99%, 98%, 97%, 96%, 95%, 90%, 85%, or 80% identity to CΨCGAGCΨGGΨ ACΨGCAΨGCA CGCAAΨGCΨA GCΨGCCCCΨΨ ΨCCCGΨCCΨG GGΨACCCCGA GΨCΨCCCCCG ACCΨCGGGΨC CCAGGΨAΨGC ΨCCCACCΨCC ACCΨGCCCCA CΨCACCACCΨ CΨGCΨAGΨΨC CAGACACCΨC CCAAGCACGC AGCAAΨGCAG CΨCAAAACGC ΨΨAGCCΨAGC CACACCCCCA CGGGAAACAG CAGΨGAΨΨAA CCΨΨΨAGCAA ΨAAACGAAAG ΨΨΨAACΨAAG CΨAΨACΨAAC CCCAGGGΨΨG GΨCAAΨΨΨCG ΨGCCAGCCAC ACCCΨGGAGC ΨAGC. E45. A nucleic acid according to any one of the preceding embodiments, wherein the at least one heterologous 5’-UTR comprises or consists of a nucleic acid sequence having at least, at most, exactly, or between any two of 99%, 98%, 97%, 96%, 95%, 90%, 85%, or 80% identity to GAAΨAAAC ΨAGΨAΨΨCΨΨ CΨGGΨCCCCA CAGACΨCAGA GAGAACCCGC CACC. E46. A nucleic acid according to any one of the preceding embodiments, wherein the nucleic acid comprises at least one poly(A) sequence, preferably comprising 30 to 200 adenosine nucleotides and/or at least one poly(C) sequence, preferably comprising 10 to 40 cytosine nucleotides. E47. A nucleic acid according to any one of the preceding embodiments, wherein the nucleic acid is a DNA or an RNA. E48. A nucleic acid according to any one of the preceding embodiments, wherein the nucleic acid is a coding RNA. E49. A nucleic acid according to E4848, wherein the coding RNA is an mRNA, a self- replicating RNA, a circular RNA, or a replicon RNA. E50. A nucleic acid according to any one of the preceding embodiments, wherein the nucleic acid, preferably the coding RNA, is an mRNA. E51. A nucleic acid according to E5050, wherein the mRNA is not a replicon RNA or a self- replicating RNA. E52. A nucleic acid according to any one of the preceding embodiments E4949- E5151, wherein the mRNA comprises at least one poly(A) sequence comprising 30 to 200 adenosine nucleotides and the 3’ terminal nucleotide is an adenosine. E53. A nucleic acid according to any one of the preceding embodiments E4747 - E5252, wherein the RNA, preferably the coding RNA, comprises a 5’-cap structure, preferably m7G, capO, cap1 , cap2, a modified capO or a modified cap1 structure, preferably a 5’- cap1 structure. E54. A nucleic acid according to any one of the preceding embodiments E4747 - E5353, wherein the RNA is codon-optimized. E55. A nucleic acid according to any one of the preceding embodiments E4747 - E5454, wherein the RNA comprises a chemically modified nucleotide. E56. A nucleic acid according to any one of the preceding embodiments E4747 - E5555, wherein the RNA comprises N1-methylpseudouridine substitution. Preferably, all the uridines of the RNA are replaced by N1-methylpseudouridine. E57. A nucleic acid according to any one of the preceding embodiments E4747 - E5686, wherein the RNA is a purified RNA, preferably an RNA that has been purified by RP-HPLC and/or TFF. E58. A nucleic according to any one of the preceding embodiments E47 to E57 wherein the RNA comprises the nucleic acid sequence of any of SEQ ID NO:20, SEQ ID NO:22, SEQ ID NO:24; SEQ ID NO:26 or SEQ ID NO:28. E59. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E4242 - E5758. E60. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E4242 - E5758, wherein the composition comprises at least one pharmaceutically acceptable carrier. E61. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E4242 - E5758, wherein the composition is a multivalent composition comprising a plurality or at least more than one of the nucleic acid according to any one of E42 to E58. E62. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E4242 - E5758, wherein the composition comprises RNA with an RNA integrity of 70% or more. E63. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E4242 - E5758, wherein the composition comprises RNA with a capping degree of 70% or more, preferably wherein at least 70%, 80%, or 90% of the mRNA species comprise a Cap1 structure. E64. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E4242 - E5758, wherein the at least one nucleic acid is complexed or associated with or at least partially complexed or partially associated with one or more cationic or polycationic compound, preferably cationic or polycationic polymer, cationic or polycationic polysaccharide, cationic or polycationic lipid, cationic or polycationic protein, cationic or polycationic peptide, or any combinations thereof. E65. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E4242 - E5758, wherein the at least one nucleic acid is complexed or associated with one or more lipids or lipid-based carriers, thereby forming liposomes, lipid nanoparticles (LNP), lipoplexes, and/or nanoliposomes, preferably encapsulating the at least one nucleic acid. E66. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E4242 - E5758, wherein the at least one nucleic acid is complexed with one or more lipids thereby forming lipid nanoparticles. E67. A composition according to any one of the preceding embodiments E65 - E6666 , wherein the LNP comprises a cationic lipid according to formula III-3: E68. A composition according to any one of the preceding embodiments E6565 -E6767, wherein the LNP comprises a PEG lipid of formula (IVa): E69. A composition according to embodiment E6868, wherein n has a mean value ranging from 30 to 60, preferably wherein n has a mean value of about 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, most preferably wherein n has a mean value of 49 or 45. E70. A composition according to any one of the preceding embodiments E6567 -E6969, wherein the LNP comprises a PEG lipid of formula (IVa): wherein n is an integer selected such that the average molecular weight of the PEG lipid is about 2500g/mol. E71. A composition according to any one of the preceding embodiments E6565 -E7070, wherein the LNP comprises one or more neutral lipids and/or one or more steroid or steroid analogues. E72. A composition according to embodiments E6571, wherein the neutral lipid is 1,2- distearoyl-sn-glycero-3-phosphocholine (DSPC), preferably wherein the molar ratio of the cationic lipid to DSPC is in the range from about 2:1 to about 8:1. E73. A composition according to any one of the preceding embodiments E6571 -E72, wherein the steroid is cholesterol, preferably wherein the molar ratio of the cationic lipid to cholesterol is in the range from about 2:1 to about 1 :1. E74. A composition according to any one of the preceding embodiments E6565 -73, wherein the LNP comprises (i) at least one cationic lipid, preferably a lipid of formula (III), more preferably lipid Ill-3; (ii) at least one neutral lipid, preferably 1 ,2-distearoyl-sn-glycero-3- phosphocholine (DSPC); (iii) at least one steroid or steroid analogue, preferably cholesterol; and (iv) at least one polymer conjugated lipid, preferably a PEG-lipid derived from formula (IVa, with n = 49), wherein (i) to (iv) are in a molar ratio of about 20-60% cationic lipid, 5-25% neutral lipid, 25-55% sterol, and 0.5-15% PEG-lipid. E75. A composition according to any one of the preceding embodiments E6565 -E74, wherein the LNP comprises (i) at least one cationic lipid, preferably a lipid of formula (III), more preferably lipid Ill-3; (ii) at least one neutral lipid, preferably 1 ,2-distearoyl-sn-glycero-3- phosphocholine (DSPC); (iii) at least one steroid or steroid analogue, preferably cholesterol; and (iv) at least one polymer conjugated lipid, preferably a PEG-lipid derived from formula (IVa, with n = 45), wherein (i) to (iv) are in a molar ratio of about 20-60% cationic lipid, 5-25% neutral lipid, 25-55% sterol, and 0.5-15% PEG-lipid. E76. A composition according to any one of the preceding embodiments E74-E75, wherein (i) to (iv) are in a molar ratio of about 50:10:38.5:1.5, preferably 47.5:10:40.8:1.7 or more preferably 47.4:10:40.9:1.7. E77. A composition according to any one of the preceding embodiments E6560 -E76, wherein the nucleic acid is RNA and the composition comprises less than about 20% free (non complexed or non-encapsulated) RNA, preferably less than about 15% free RNA, more preferably less than about 10% free RNA. E78. A composition according to any one of the preceding embodiments E6565 -E77, wherein the wt/wt ratio of lipid to nucleic acid is from about 10:1 to about 60:1 , preferably from about 20:1 to about 30:1 , for example about 25:1. E79. A composition according to any one of the preceding embodiments E6565 -E78, wherein the n/p ratio of the LNPs encapsulating the nucleic acid is in a range from about 1 to about 10, preferably in a range from about 5 to about 7, more preferably about 6. E80. A composition according to any one of the preceding embodiments E6565 -E79, wherein the composition has a polydispersity index (PDI) value of less than about 0.4, preferably of less than about 0.3, more preferably of less than about 0.2, most preferably of less than about 0.1. E81. A composition according to any one of the preceding embodiments E6565 -E80, wherein the LNPs have a Z-average size in a range of about 60nm to about 120nm, preferably less than about 120nm, more preferably less than about 100nm, most preferably less than about 80nm. E82. A composition according to any one of the preceding embodiments E6565 -E81, wherein the LNPs comprise less than about 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1% LNPs that have a particle size exceeding about 500nm. E83. A composition according to any one of the preceding embodiments E65-E82, wherein the LNPs comprise less than about 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1% LNPs that have a particle size smaller than about 20nm. E84. A composition according to any one of the preceding embodiments E6565 -E83, wherein the LNP comprises (i) at least one cationic lipid; (ii) at least one neutral lipid; (iii) at least one steroid or steroid analogue; and (iv) at least one PEG-lipid, wherein (i) to (iv) are in a molar ratio of about 20-60% cationic lipid, 5-25% neutral lipid, 25-55% sterol, and 0.5-15% PEG-lipid. E85. A composition according to any one of the preceding embodiments E6565 -E84, wherein the LNP comprises (i) at least one cationic lipid according to formula III-3; (ii) DSPC; (iii) cholesterol; and (iv) a PEG-lipid, according to formula IVa, wherein (i) to (iv) are in a molar ratio of about 20-60% cationic lipid, 5-25% neutral lipid, 25-55% sterol, and 0.5-15% PEG-lipid. E86. A composition according to any one of the preceding embodiments E5959-E85, wherein the composition is a lyophilized composition. E87. An immunogenic composition comprising a mutant according to any one of E1 to E41, a nucleic acid according to any one of E42 to E58 or a composition according to any one of E59 to E86. E88. An immunogenic composition according to E87 comprising a mutant according to any one of E1 to E41, a nucleic acid according to any one of E42 to E58 or a composition according to any one of E59 to E86 wherein the wild-type hMPV F protein is of subtype A and, a mutant according to any one of E1 to E41, a nucleic acid according to any one of E42 to E58 or a composition according to any one of E59 to E86 wherein the wild-type hMPV F protein is of subtype B. E89. An immunogenic composition according to any one of embodiments E87-E88, further comprising a PIV1 antigen selected from the group consisting of a mutant of a wild-type PIV1 F protein and a nucleic acid encoding a mutant of a wild-type PIV1 F protein. E90. An immunogenic composition according to embodiment E89, wherein the PIV1 antigen is a mutant of a wild-type PIV1 F protein. E91. An immunogenic composition according to embodiment E90, wherein the PIV1 antigen is a mutant of a wild-type PIV1 F protein from the present disclosure, preferably from any of E1 to E46 of section C.1 of the present disclosure. E92. An immunogenic composition according to embodiment E90, wherein the PIV1 antigen comprises a nucleic acid encoding a mutant of a wild-type PIV1 F protein. E93. An immunogenic composition according to embodiment E92, wherein the PIV1 antigen comprises a nucleic acid encoding a mutant of a wild-type PIV1 F protein from the present disclosure, preferably from any of E47 to E62 of section C.1 of the present disclosure. E94. An immunogenic composition according to any one of embodiments E8787 to E9393, further comprising PIV3 antigen selected from the group consisting of a mutant of a wild-type PIV3 F protein and a nucleic acid encoding a mutant of a wild-type PIV3 F protein. E95. An immunogenic composition according to embodiment E94, wherein the PIV3 antigen is a mutant of a wild-type PIV3 F protein. E96. An immunogenic composition according to embodiment E95, wherein the PIV3 antigen is a mutant of a wild-type PIV3 F protein from the present disclosure, preferably from any of E1 to E52 of section C.2 of the present disclosure. E97. An immunogenic composition according to embodiment E95, wherein the PIV3 antigen is a mutant of a wild-type PIV3 F protein as disclosed in WO2018081289 or WO2022207839. E98. An immunogenic composition according to embodiment E95, wherein the PIV3 antigen comprises a nucleic acid encoding a mutant of a wild-type PIV3 F protein. E99. An immunogenic composition according to embodiment E95, wherein the PIV3 antigen comprises a nucleic acid encoding a mutant of a wild-type PIV3 F protein from the present disclosure, preferably from any of E53 to E69 of section C.2 of the present disclosure. E100. An immunogenic composition according to embodiment E98, wherein the PIV3 antigen comprises a nucleic acid encoding a mutant of a wild-type PIV3 F protein as disclosed in WO2018081289 or WO2022207839. E101. An immunogenic composition according to any one of E8787 to 100, further comprising an RSV antigen selected from the group consisting of a mutant of a wild-type RSV F protein of subtype A and a nucleic acid encoding a mutant of a wild-type RSV F protein of subtype A. E102. An immunogenic composition according to embodiment E101, wherein the RSV antigen is a mutant of a wild-type RSV F protein of subtype A. E103. An immunogenic composition according to embodiment E101, wherein the RSV antigen is a nucleic acid encoding a mutant of a wild-type RSV F protein of subtype A. E104. An immunogenic composition according to embodiments E101-103, wherein the mutant of a wild-type RSV F protein of subtype A is disclosed in one of WO2009/079796, WO2010/149745, WO2011/008974, WO2014/160463, WO2014/174018, WO2014/202570, WO2015/013551, WO2015/177312, WO2017/005848, WO2017/174564, WO2017/005844, WO2017/109629, WO2022/002894 and WO2018/109220. E105. An immunogenic composition according to any one of embodiments E8787 to E104, further comprising an RSV antigen selected from the group consisting of a mutant of a wild- type RSV F protein of subtype B and a nucleic acid encoding a mutant of a wild-type RSV F protein of subtype B. E106. An immunogenic composition according to embodiment E105, wherein the RSV antigen is a mutant of a wild-type RSV F protein of subtype B. E107. An immunogenic composition according to embodiment E105, wherein the RSV antigen comprises a nucleic acid encoding a mutant of a wild-type RSV F protein of subtype B. E108. An immunogenic composition according to embodiment E105 or E107, wherein the mutant of a wild-type RSV F protein of subtype B is disclosed in one of WO2009/079796, WO2010/149745, WO2011/008974, WO2014/160463, WO2014/174018, WO2014/202570, WO2015/013551, WO2015/177312, WO2017/005848, WO2017/174564, WO2017/005844, WO2017/109629, WO2022/002894 and WO2018/109220. 2. HMPV F PROTEIN MUTANTS In some aspects, the present invention provides mutants of wild-type hMPV F proteins, wherein the mutants display introduced mutations in the amino acid sequence relative to the amino acid sequence of the corresponding wild-type hMPV F protein and are immunogenic against the wild-type hMPV F protein in the prefusion conformation or against a virus comprising the wild-type F protein. In certain embodiments, the hMPV F mutants possess certain beneficial characteristics, such as increased immunogenic properties or improved stability in the prefusion conformation of the mutants or prefusion trimeric conformation of the mutant, as compared to the corresponding wild-type F protein. The present disclosure provides hMPV F mutants that display at least the mutation of a pair of amino acid residues in a wild- type hMPV F protein to a pair of cysteines (”engineered interprotomer disulfide mutation”) and bind to a prefusion specific antibody selected from MPE8 mAb or hMPV-2 mAb. The introduced pair of cysteine residues allows for formation of interprotomer disulfide bonds (disulfide bond between the introduced cysteine residues of different protomers of the trimer) that stabilize the protein’s conformation or oligomeric state, such as the prefusion conformation and the trimeric structure. The introduced amino acid mutations in the hMPV F protein mutants mays also include amino acid substitutions, deletions, or additions. In some embodiments, the only mutations in the amino acid sequence of the mutants are amino acid substitutions relative to a wild-type hMPV F protein. The amino acid sequence of a large number of native hMPV F proteins from different hMPV subtypes, as well as nucleic acid sequences encoding such proteins, is known in the art. For example, the sequence of several subtype A and B hMPV F0 precursor proteins are set forth in SEQ ID NOs:1 to 7. The native hMPV F protein exhibits remarkable sequence conservation across hMPV subtypes. For example, hMPV subtypes A and B consensus sequences share about 94% sequence identity across the F0 precursor molecule. Nearly all identified hMPV F0 precursor sequences consist of 539 amino acids in length, with minor differences in length. Sequence identity across various native hMPV F proteins is known in the art (see, for example, Yang et al, Virology Journal 2009, 6:138). In view of the substantial conservation of hMPV F protein sequences, a person of ordinary skill in the art can easily compare amino acid positions between different native hMPV F protein sequences to identify corresponding hMPV F protein amino acid positions between different hMPV strains and subtypes. For example, across nearly all identified native hMPV F0 precursor proteins, the protease cleavage site falls in the same amino acid positions. Thus, the conservation of native hMPV F protein sequences across strains and subtypes allows use of a reference hMPV F protein sequence for comparison of amino acids at particular positions in the hMPV F protein. For the purposes of this disclosure (unless context indicates otherwise), the hMPV F protein amino acid positions are given with reference to the sequence of the F0 precursor polypeptide set forth in SEQ ID NO: 1 (the amino acid sequence of the full length native F precursor polypeptide of the hMPV A2b strain; corresponding to Genbank Identifier ACJ53569.1 (amino acids) and EU857558.1 (nucleotides). For the purposes of this disclosure (unless context indicates otherwise), the hMPV A F protein amino acid positions are given with reference to the sequence of the F0 precursor polypeptide set forth in SEQ ID NO: 1 (the amino acid sequence of the full length native F precursor polypeptide of the hMPV A2b strain; corresponding to Genbank Identifier ACJ53569.1 (amino acids) and EU857558.1 (nucleotides)). For the purposes of this disclosure (unless context indicates otherwise), the hMPV B F protein amino acid positions are given with reference to the sequence of the F0 precursor polypeptide set forth in SEQ ID NO: 7 (the amino acid sequence of the full length native F precursor polypeptide of the hMPV B strain; corresponding to Genbank Identifier ANW37992.1 (amino acids)). The consensus sequence for hMPV B was obtained as follows: Whole genome sequences for hMPV B were downloaded from NCBI’s GenBank database as GenBank file format. Fusion protein gene sequences were filtered by sequence length to only include complete coding DNA sequence features. Translated fusion protein sequences were then parsed from GenBank file and saved as FASTA file. Muscle v5 was used to perform multiple sequence alignment of collected sequences. A Position specific score matrices (PSSMs) was generated to summarize the alignment information. For each column in the alignment, the number of each amino acid letters is counted and totaled. The consensus sequence at each position was calculated as the most common amino acid type in PSSM table. The final consensus sequence was then extracted and saved as FASTA file. However, it should be noted, and one of skill in the art will understand, that different hMPV F0 sequences may have different numbering systems, for example, if there are additional amino acid residues added or removed as compared to SEQ ID NO:1. As such, it is to be understood that when specific amino acid residues are referred to by their number, the description is not limited to only amino acids located at precisely that numbered position when counting from the beginning of a given amino acid sequence, but rather that the equivalent/corresponding amino acid residue in any and all hMPV F sequences is intended even if that residue is not at the same precise numbered position, for example if the hMPV sequence is shorter or longer than SEQ ID NO:1, or has insertions or deletions as compared to SEQ ID NO: 1. 2-1. Structure of the hMPV F Protein Mutants The hMPV F protein mutants provided by the present disclosure comprise a F1 polypeptide and a F2 polypeptide. In several embodiments, the mutants further comprise a trimerization domain. In some embodiments, either the F1 polypeptide or the F2 polypeptide includes at least one introduced modification (e.g., amino acid substitution) as described in detail herein below. In some other embodiments, each of the F1 polypeptide and F2 polypeptide includes at least one introduced modification (e.g., amino acid substitution) as described in detail herein below. 2-1(a). F1 Polypeptide and F2 Polypeptide of the hMPV F Mutants In some embodiments, the mutants are in the mature form of the hMPV F protein, which comprises two separate polypeptide chains, namely the F1 polypeptide and F2 polypeptide. The F1 polypeptide chain of the mutant may be of the same length as the full length F1 polypeptide of the corresponding wild-type hMPV F protein; however, it may also have deletions, such as deletions of 1 up to 36 amino acid residues from the C-terminus of the full- length F1 polypeptide. A full-length F1 polypeptide of the hMPV F mutants corresponds to amino acid positions 103-539 of the native hMPV F0 precursor, and includes (from N- to C- terminus) an extracellular region (residues 103 to 489), a transmembrane domain (residues 490-514), and a cytoplasmic domain (residues 515-539). It should be noted that amino acid residues 490 onwards in a native F1 polypeptide sequence are optional sequences in a F1 polypeptide of the hMPV F mutants provided herein, and therefore may be absent from the F1 polypeptide of the mutant. In some embodiments, the F1 polypeptide of the hMPV F mutants lacks the entire cytoplasmic domain. In other embodiments, the F1 polypeptide lacks the cytoplasmic domain and a portion of or all entire transmembrane domain. In some specific embodiments, the mutant comprises a F1 polypeptide wherein the amino acid residues from position 490 through 539 are absent. Typically, for mutants that are linked to trimerization domain, such as a foldon, amino acids 490 through 539 can be absent. Thus, in some specific embodiment, amino acid residues 490 through 539 are absent from the F1 polypeptide of the mutant. In still other specific embodiments, the F1 polypeptide of the hMPV F mutants comprises or consists of amino acid residues 103-489 of a native F0 polypeptide sequence, such as any of the F0 precursor sequence set forth in SEQ ID NOs: 1 to 7. On the other hand, the F1 polypeptide of the hMPV F mutant may include a C-terminal linkage to a trimerization domain, such as a foldon. Many of the sequences of the hMPV F mutants disclosed herein include a sequence of a PreScission cleavage site and Strep Tag II that are not essential for the function of the hMPV F protein, such as for induction of an immune response. A person skilled in the art will recognize such sequences, and when appropriate, understand that these sequences are not included in a disclosed hMPV F mutant. In the hMPV F mutants provided by the present disclosure, the F2 polypeptide chain may be of the same length as the full-length F2 polypeptide of the corresponding wild-type hMPV F protein; it may also have deletions, such as deletions of 1, 2, 3, 4, 5, 6, 7, or 8 amino acid residues from the N-terminus or C-terminus of the F2 polypeptide. The mutant in F0 form (i.e., a single chain polypeptide comprising the F2 polypeptide joined to the F1 polypeptide) or F1-F2 heterodimer form may form a protomer. The mutant may also be in the form of a trimer, which comprises three of the same protomer. Further, the mutants may be glycosylated proteins (i.e., glycoproteins) or non-glycosylated proteins. The mutant in F0 form may include, or may lack, the signal peptide sequence. The F1 polypeptide and F2 polypeptide of the hMPV F protein mutants to which one or more mutations are introduced can be from any wild-type hMPV F proteins known in the art or discovered in the future, including, without limitations, the F protein amino acid sequence of hMPV subtype A, and subtype B strains, or any other subtype. In some embodiments, the hMPV F mutant comprises a F1 and/or a F2 polypeptide from a hMPV A virus, for example, a F1 and/or F2 polypeptide from a known hMPV F0 precursor protein such for example those set forth in any one of SEQ ID NOs: 1 to 3 to which one or more mutations are introduced. In some other embodiments, the hMPV F mutant comprises a F1 and/or a F2 polypeptide from a hMPV B virus, for example, a F1 and/or F2 polypeptide from a known hMPV F0 precursor protein such as those set forth in any one of SEQ ID NOs: 4 to 7 to which one or more mutations are introduced. In some embodiments, the hMPV F protein mutants comprise a F1- polypeptide, a F2 polypeptide, and one or more introduced amino acid mutations as described herein below, wherein the F1 polypeptide comprises 350 consecutive amino acids and is at least 90, 95, 98, or 99 percent identical to amino acids 103-489 of any of the sequence of SEQ ID NO:1 to 3, wherein the F2 polypeptide comprises 70 consecutive amino acids and is at least 90, 95, 98, or 99 percent identical to amino acids 21-102 of any of the sequence of SEQ ID NO:1 to 3 and wherein hMPV F protein mutant is stabilized in prefusion trimer conformation, whether as monomer or trimer. In some embodiments, the hMPV F protein mutants comprise a F1- polypeptide, a F2 polypeptide, and one or more introduced amino acid mutations as described herein below, wherein the F1 polypeptide comprises 350 consecutive amino acids and is at least 90, 95, 98, or 99 percent identical to amino acids 103-489 of any of the sequence of SEQ ID NO:4 to 7, wherein the F2 polypeptide comprises 70 consecutive amino acids and is at least 90, 95, 98, or 99 percent identical to amino acids 21-102 of any of the sequence of SEQ ID NO:4 to 7 and wherein hMPV F protein mutant is stabilized in prefusion trimer conformation, whether as monomer or trimer. 2-1(b) Trimerization Domains In several embodiments, the hMPV F mutant provided by the present disclosure is linked to a trimerization domain. In some embodiments, the trimerization domain promotes the formation of trimer of three F1/F2 heterodimers. Several exogenous trimerization domains that promote formation of stable trimers of soluble proteins are known in the art. Non limiting examples of such trimerization domains that can be linked to a mutant provided by the present disclosure include: (1) the GCN4 leucine zipper (Harbury et al.1993 Science 262: 1401-1407); (2) the trimerization motif from the lung surfactant protein (Hoppe et al.1994 FEB S Lett 344: 191-195); (3) collagen (McAlinden et al. 2003 Biol Chem 278:42200-42207); and (4) the phage T4 fibritin foldon (Miroshnikov et al. 1998 Protein Eng 11:329-414). Typically, the trimerization domain is positioned C-terminal to the F1 polypeptide. It may join directly to the F1 polypeptide chain. Optionally, the multimerization domain is connected to the F1 polypeptide via a linker, such as an amino acid linker, for example the sequence GG, GS, GGGS, or SAIG. The linker can also be a longer linker (for example, including the repeat sequence GG). A preferred linker is GGGS. Numerous conformationally neutral linkers are known in the art that can be used in the mutants provided by the present disclosure. In some embodiments, the F mutant comprising a foldon domain include a protease cleavage site for removing the foldon domain from the F1 polypeptide, such as a thrombin site between the F1 polypeptide and the foldon domain. In some embodiments, a foldon domain is linked to a F mutant at the C-terminus of F1 polypeptide. In specific embodiments, the foldon domain is a T4 fibritin foldon domain, such as the amino acid sequence GYIPEAPRDGQAYVRKDGEWVLLSTFL (SEQ ID NO: 8). 2-2. Introduced Mutations in the hMPV F Protein Mutants The hMPV F mutants provided by the present disclosure comprise a F1 polypeptide and a F2 polypeptide, wherein (1) either the F1 polypeptide or (2) the F2 polypeptide, or (3) both the F1 polypeptide and F2 polypeptide include one or more introduced amino acid mutations relative to the amino acid sequence of the corresponding native F protein. The introduction of such amino acid mutations in the hMPV F mutants confers a beneficial property to the mutants, such as enhanced immunogenicity, improved stability, improved expression or formation or improved stability of certain desired physical form or conformation of the mutants. Such introduced amino acid mutations are referred to as “engineered interprotomer disulfide mutations”, “engineered disulfide bond mutations”, “cavity filling mutations”, ” proline substitution mutations” or “glycine replacement mutation”, and are described in detail herein below. hMPV F mutants that include any additional mutations are also encompassed by the invention so long as the immunogenic property of the mutants is not substantially adversely affected by the additional mutations. 2-2(a) Engineered Interprotomer Disulfide Bond Mutations The hMPV F mutants provided by the present disclosure include one or more engineered interprotomer disulfide bond mutations. The term “engineered interprotomer disulfide bond mutation” refers to mutation of a pair of amino acid residues in a wild-type hMPV F protein to a pair of cysteine residues selected so that an interprotomer disulfide bond is formed when the F protein is in the prefusion conformation and forms a trimer. Said interprotomer disulfide bonds stabilize the protein’s conformation or oligomeric state, such as the prefusion conformation and the trimeric structure. For stabilizing the prefusion conformation and trimeric structure of the mutant, the residue pairs for mutation to cysteine should be in close proximity when the protomers are in the prefusion conformation and form a trimer but distant in the post-fusion conformation. Preferably, the distance between the pair of residues (e.g. the beta carbons) is less than 8 Å in a prefusion conformation, but more than 20 Å in a post-fusion conformation. In some specific embodiments, the present disclosure provides a hMPV F mutant comprising at least one engineered interprotomer disulfide bond mutation, wherein the mutant comprises the same introduced mutations that are the exemplary mutants provided in Table 2. The exemplary hMPV F mutants provided in Table 2 are based on the same native F0 sequence of hMPV B strain (SEQ ID NO:32). The same introduced mutations in each of the mutants can be made to a native F0 polypeptide sequence of any other hMPV subtype or strain to arrive at different hMPV F mutants, such as a native F0 polypeptide sequence set forth in any of the SEQ ID NOs: 1 to 7 or from any other hMPV A or B strain. hMPV F mutants that are based on a native F0 polypeptide sequence of any other hMPV subtype or strain and comprise any of the engineered interprotomer disulfide mutations are also within the scope of the invention. In some particular embodiments, a hMPV F protein mutant comprises at least one engineered interprotomer disulfide mutation selected from the group consisting of (1) 69C and 195C; (2) 80C and 224C; (3) 211C and 250C; (4) 337C and 423C; and, (5) 111C and 323C. 2-2(b) Engineered Disulfide Bond Mutations In some embodiments, the hMPV F mutants of the present disclosure may comprise one or more engineered disulfide bond mutations. The term “engineered disulfide bond mutation” refers to mutation of a pair of amino acid residues in a wild-type hMPV F protein to a pair of cysteine residues. The introduced pair of cysteine residues allows for formation of a disulfide bond between the introduced cysteine residues, which disulfide bond serves to stabilize the protein’s conformation or oligomeric state, such as prefusion conformation. For stabilizing the prefusion conformation of the mutant, the residue pairs for mutation to cysteine should be in close proximity in the prefusion conformation but distant in the post-fusion conformation. Preferably, the distance between the pair of residues (e.g. the beta carbons) is less than 8 Å in a prefusion conformation, but more than 20 Å in a post-fusion conformation. In some particular embodiments, the hMPV F protein mutant comprises at least one engineered disulfide mutation selected from the group consisting of: 366C and 454C, 411C and 434C, 137C and 159C, 140C and 149C, 141C and 159C, 141C and 161C, 146C and 160C, 148C and 158C and 150C and 156C, such as G366C and D454C, T411C and Q434C, I137C and A159C, A140C and S149C, L141C and A159C, L141C and A161C, E146C and T160C, V148C and L158C and T150C and R156C. 2-2(c) Cavity Filling Mutations. In other embodiments, the hMPV F mutants of the present disclosure may comprise one or more cavity filling mutations. The term “cavity filling mutation” refers to the substitution of an amino acid residue in the wild-type hMPV F protein by an amino acid that is expected to fill an internal cavity of the mature hMPV F protein. In one application, such cavity-filling mutations contribute to stabilizing the prefusion conformation of a hMPV F protein mutant. For example, the amino acids to be replaced for cavity-filling mutations typically include small aliphatic (e.g. Gly, Ala, and Val) or small polar amino acids (e.g. Ser and Thr). They may also include amino acids that are buried in the prefusion conformation, but exposed to solvent in the post-conformation. The replacement amino acids can be aliphatic amino acids (Val, Ile, Leu and Met), aromatic amino acid (His, Phe, Tyr and Trp), polar amino acids (Thr) with greater size than the replaced amino acids. In some specific embodiments, the hMPV F protein mutant comprises one or more cavity filling mutations selected from the group consisting of: (1) substitution of the amino acid at position 49, 291 or 365 with I, V, L, M, F, Y, H; (2) substitution of the amino acid at position 149 with T, V, or I; (3) substitution of the amino acid at position 159 with V, I or L; (4) substitution of the amino acid at position 473 with F or W; In some particular embodiments, the hMPV F protein mutant comprises at least one cavity filling mutation selected from the group consisting of: T49I, S149T or T365I. 2-2 (d) Proline substitution mutations. In other embodiments, the hMPV F mutants of the present disclosure may comprise one or more proline substitution mutations. The term proline substitution mutations” refers to the substitution of an amine acid by a proline to prevent the structural refolding that occurs during transit from the prefusion to post-fusion conformation In some specific embodiments, the hMPV F protein mutant comprises at least one proline substitution mutations selected from the group consisting of 66P, 110P, 132P, 145P, 187P, 449P and 459P, such as L66P, L110P, S132P, N145P, L187P, V449P and A459P. In some particular embodiments, the hMPV F protein mutant comprises mutation A459P. In some particular embodiments, the hMPV F protein mutant comprises mutation L66P or L187P. 2-2 (e) Glycine replacement mutations. In other embodiments, the hMPV F mutants of the present disclosure may comprise one or more glycine replacement mutation. The term “glycine replacement mutation” refers to the replacement of a glycine by another amino acid in the middle of an α-helix to improve protein stability, preferably an amino acid without Cβ substitution, such as Ala , Leu or Met. In some specific embodiments, the hMPV F protein mutant comprises at least one glycine replacement mutation selected from the group consisting of G106A, G121A and G239A. In some particular embodiments, the hMPV F protein mutant comprises mutation G239A. 2-2 (f) Other mutations In some particular embodiments, the hMPV F protein mutant comprises any of the above disclosed mutation or combination of mutations in combination with Q100R and S101R. In some particular embodiments, the hMPV F protein mutant comprises any of the above disclosed mutation or combination of mutations in combination with any mutation disclosed in WO2022076669, such as for example E26C and G439C; N46C and L158C, T49C and A161C, L50C and V162C, E51C and R163C; E51C and K166C; V104C and N457C, L110C and N322C, A113C and D336C, A116C and A338C, A140C and A147C, S291C and S443C; S293C and S443C; S293C and S444C; S355C and V442C; T365C and V463C, S22C and H435C; G53C and K166C; G53C and V169C; E305C and N457C; S291C and L302C, V47C and A159C; T127C and N153C, G121C and I/F258C, F48C and T160C, and/or T365C and Q455C, L219K, V2311, S376T, G366S, S194Q, K166E, T49E, L187F, L473F, S347Q, H435E, H435D or H435N, G106W, A107F, T160M, L158W, I128F, A190M, V118F, V118M, Q426W, L165F, V191I, T160V, S149V, I137L, S149I, V169I, N46V, T49I, V/I122L, S192L, T317L, V162F, V162W, L105I, L105F, L105W, L134I, A117M, S347M, S347K, S347Q, V47M, G261M, I268M, S470Y, V231I, A374V, I217V, S355F, A86P, A107P, A113P, T114P, V148P, S443P, D461P, L130P, L141P, K142P, E146P, L151P, N153P, V162P, A/D185P, D186P, L187P, K188P, N342P, A344P, L66N, L73E, N145E, Q195K, E453Q, L66D, K188R, H368R, D461E, T49E, V262D. In some other particular embodiments, the present invention provides a hMPV F mutant, wherein (a) the mutant comprises a cysteine (C) at position 69 (69C) and at position 195 (195C), and wherein the mutant comprises a F1 polypeptide and a F2 polypeptide selected from the group consisting of: (1) a F2 polypeptide comprising the amino acid sequence of SEQ ID NO:10 and a F1 polypeptide comprising the amino acid sequence of SEQ ID NO:9; (2) a F2 polypeptide comprising an amino acid sequence that is at least 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:10 and a F1 polypeptide comprising an amino acid sequence that is at least 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:9 or; (b) the mutant comprises a cysteine (C) at position 80 (80C) and at position 224 (224C), and wherein the mutant comprises a F1 polypeptide and a F2 polypeptide selected from the group consisting of: (1) a F2 polypeptide comprising the amino acid sequence of SEQ ID NO:12 and a F1 polypeptide comprising the amino acid sequence of SEQ ID NO:11; (2) a F2 polypeptide comprising an amino acid sequence that is at least 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:12 and a F1 polypeptide comprising an amino acid sequence that is at least 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:11 or; (c) the mutant comprises a cysteine (C) at position 211 (211C) and at position 250 (250C), and wherein the mutant comprises a F1 polypeptide and a F2 polypeptide selected from the group consisting of: (1) a F2 polypeptide comprising the amino acid sequence of SEQ ID NO:14 and a F1 polypeptide comprising the amino acid sequence of SEQ ID NO:13; (2) a F2 polypeptide comprising an amino acid sequence that is at least 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:14 and a F1 polypeptide comprising an amino acid sequence that is at least 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:13 or; (d) the mutant comprises a cysteine (C) at position 337 (337C) and at position 423 (423C), and wherein the mutant comprises a F1 polypeptide and a F2 polypeptide selected from the group consisting of: (1) a F2 polypeptide comprising the amino acid sequence of SEQ ID NO:16 and a F1 polypeptide comprising the amino acid sequence of SEQ ID NO:15; (2) a F2 polypeptide comprising an amino acid sequence that is at least 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:16 and a F1 polypeptide comprising an amino acid sequence that is at least 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:15 or; (e) the mutant comprises a cysteine (C) at position 111 (111C) and at position 323 (323C), and wherein the mutant comprises a F1 polypeptide and a F2 polypeptide selected from the group consisting of: (1) a F2 polypeptide comprising the amino acid sequence of SEQ ID NO:18 and a F1 polypeptide comprising the amino acid sequence of SEQ ID NO:17; (2) a F2 polypeptide comprising an amino acid sequence that is at least 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:18 and a F1 polypeptide comprising an amino acid sequence that is at least 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:17. The hMPV F protein mutants provided by the present disclosure can be prepared by routine methods known in the art, such as by expression in a recombinant host system using a suitable vector. Suitable recombinant host cells include, for example, insect cells, mammalian cells, avian cells, bacteria, and yeast cells. Examples of suitable insect cells include, for example, Sf9 cells, Sf21 cells, Tn5 cells, Schneider S2 cells, and High Five cells (a clonal isolate derived from the parental Trichoplusia ni BTI-TN-5B1-4 cell line (Invitrogen)). Examples of suitable mammalian cells include Chinese hamster ovary (CHO) cells, human embryonic kidney cells (HEK293 or Expi293 cells, typically transformed by sheared adenovirus type 5 DNA), NIH-3T3 cells, 293-T cells, Vero cells, and HeLa cells. Suitable avian cells include, for example, chicken embryonic stem cells (e.g., EBx.RTM. cells), chicken embryonic fibroblasts, chicken embryonic germ cells, quail fibroblasts (e.g. ELL-O), and duck cells. Suitable insect cell expression systems, such as baculovirus-vectored systems, are known to those of skill in the art and described in, e.g., Summers and Smith, Texas Agricultural Experiment Station Bulletin No.1555 (1987). Materials and methods for baculovirus/insect cell expression systems are commercially available in kit form from, inter alia, Invitrogen, San Diego Calif. Avian cell expression systems are also known to those of skill in the art and described in, e.g., U.S. Pat. Nos.5,340,740; 5,656,479; 5,830,510; 6,114,168; and 6,500,668. Similarly, bacterial and mammalian cell expression systems are also known in the art and described in, e.g., Yeast Genetic Engineering (Barr et al., eds., 1989) Butterworths, London. A number of suitable vectors for expression of recombinant proteins in insect or mammalian cells are well-known and conventional in the art. Suitable vectors can contain a number of components, including, but not limited to one or more of the following: an origin of replication; a selectable marker gene; one or more expression control elements, such as a transcriptional control element (e.g., a promoter, an enhancer, a terminator), and/or one or more translation signals; and a signal sequence or leader sequence for targeting to the secretory pathway in a selected host cell (e.g., of mammalian origin or from a heterologous mammalian or non-mammalian species). For example, for expression in insect cells a suitable baculovirus expression vector, such as pFastBac (Invitrogen), is used to produce recombinant baculovirus particles. The baculovirus particles are amplified and used to infect insect cells to express recombinant protein. For expression in mammalian cells, a vector that will drive expression of the construct in the desired mammalian host cell (e.g., Chinese hamster ovary cells) is used. The hMPV F protein mutant polypeptides can be purified using any suitable methods. For example, methods for purifying hMPV F protein mutant polypeptides by immunoaffinity chromatography are known in the art. Ruiz-Arguello et al., J. Gen. Virol., 85:3677-3687 (2004). Suitable methods for purifying desired proteins including precipitation and various types of chromatography, such as hydrophobic interaction, ion exchange, affinity, chelating, and size exclusion are well-known in the art. Suitable purification schemes can be created using two or more of these or other suitable methods. If desired, the hMPV F protein mutant polypeptides can include a "tag" that facilitates purification, such as an epitope tag, a strep II tag or a histidine (HIS) tag. Such tagged polypeptides can conveniently be purified, for example from conditioned media, by chelating chromatography or affinity chromatography. Below table 1 provides representative sequences from hMPV A and B F0 polypeptide. Table 1. F protein sequences from selected hMPV strains. Strain SEQ F0 protein sequence (subtype) / ID GenBank_aa NO TN/95/3-54 1 MSWKVVIIFSLLITPQHGLKESYLEESCSTITEGYLSVLRTGWY (A2b) / TNVFTLEVGDVENLTCADGPSLIKTELDLTKSALRELKTVSAD ACJ53569.1 QLAREEQIENPRQSRFVLGAIALGVATAAAVTAGVAIAKTIRLE SEVTAIKNALKKTNEAVSTLGNGVRVLATAVRELKDFVSKNLT RAINKNKCDIDDLKMAVSFSQFNRRFLNVVRQFSDNAGITPAI SLDLMTDAELARAVSNMPTSAGQIKLMLENRAMVRRKGFGIL IGVYGSSVIYMVQLPIFGVIDTPCWIVKAAPSCSEKKGNYACL LREDQGWYCQNAGSTVYYPNEKDCETRGDHVFCDTAAGIN VAEQSKECNINISTTNYPCKVSTGRHPISMVALSPLGALVACY KGVSCSIGSNRVGIIKQLNKGCSYITNQDADTVTIDNTVYQLS KVEGEQHVIKGRPVSSSFDPVKFPEDQFNVALDQVFENIENS QALVDQSNRILSSAEKGNTGFIIVIILIAVLGSSMILVSIFIIIKKTK KPTGAPPELSGVTNNGFIPHS CAN00- 2 MSWKVVIIFSLLITPQHGLKESYLEESCSTITEGYLSVLRTGWY 14 (A1) / TNVFTLEVGDVENLTCADGPSLIKTELDLTKSALRELRTVSAD AAN52913.1 QLAREEQIENPRQSRFVLGAIALGVATAAAVTAGVAIAKTIRLE SEVTAIKNALKKTNEAVSTLGNGVRVLATAVRELKDFVSKNLT RAINKNKCDIADLKMAVSFSQFNRRFLNVVRQFSDNAGITPAI SLDLMTDAELARAVSNMPTSAGQIKLMLENRAMVRRKGFGIL IGVYGSSVIYMVQLPIFGVIDTPCWIVKAAPSCSEKKGNYACL LREDQGWYCQNAGSTVYYPNEKDCETRGDHVFCDTAAGIN VAEQSKECNINISTTNYPCKVSTGRHPISMVALSPLGALVACY KGVSCSIGSNRVGIIKQLNKGCSYITNQDADTVTIDNTVYQLS KVEGEQHVIKGRPVSSSFDPVKFPEDQFNVALDQVFESIENS QALVDQSNRILSSAEKGNTGFIIVIILIAVLGSTMILVSVFIIIKKT KKPTGAPPELSGVTNNGFIPHN TN/00/3-1 3 MSWKVVIIFSLLITPQHGLKESYLEESCSTITEGYLSVLRTGWY (A2a) / TNVFTLEVGDVENLTCSDGPSLIKTELDLTKSALRELKTVSAD ACJ53563.1 QLAREEQIENPRQSRFVLGAIALGVATAAAVTAGVAIAKTIRLE SEVTAIKNALKTTNEAVSTLGNGVRVLATAVRELKDFVSKNLT RAINKNKCDIDDLKMAVSFSQFNRRFLNVVRQFSDNAGITPAI SLDLMTDAELARAVSNMPTSAGQIKLMLENRAMVRRKGFGIL IGVYGSSVIYMVQLPIFGVIDTPCWIVKAAPSCSEKKGNYACL LREDQGWYCQNAGSTVYYPNEKDCETRGDHVFCDTAAGIN VAEQSKECNINISTTNYPCKVSTGRHPISMVALSPLGALVACY KGVSCSIGSNRVGIIKQLNKGCSYITNQDADTVTIDNTVYQLS KVEGEQHVIKGRPVSSSFDPIKFPEDQFNVALDQVFENIENS QALVDQSNRILSSAEKGNTGFIIVIILIAVLGSSMILVSIFIIIKKTK KPTGAPPELSGVTNNGFIPHS Consensus 4 MSWKVMIIISLLITPQHGLKESYLEESCSTITEGYLSVLRTGWY hMPV B TNVFTLEVGDVENLTCTDGPSLIKTELDLTKSALRELKTVSAD QLAREEQIENPRQSRFVLGAIALGVATAAAVTAGIAIAKTIRLE SEVNAIKGALKTTNEAVSTLGNGVRVLATAVRELKEFVSKNLT SAINKNKCDIADLKMAVSFSQFNRRFLNVVRQFSDNAGITPAI SLDLMNDAELARAVSYMPTSAGQIKLMLENRAMVRRKGFGIL IGVYGSSVIYMVQLPIFGVINTPCWIIKAAPSCSEKDGNYACLL REDQGWYCKNAGSTVYYPNEKDCETRGDHVFCDTAAGINV AEQSRECNINISTTNYPCKVSTGRHPISMVALSPLGALVACYK GVSCSIGSNQVGIIKQLPKGCSYITNQDADTVTIDNTVYQLSK VEGEQHVIKGRPVSSSFDPIRFPEDQFNVALDQVFESIENSQ ALVDQSNKILNSAEKGNTGFIIVIILIAVLGLTMISVSIIIIIKKTRKP TGAPPELNGVTNGGFIPHS JPS03-194 5 MSWKVMIIISLLITPQHGLKESYLEESCSTITEGYLSVLRTGWY (B1) / TNVFTLEVGDVENLTCTDGPSLIKTELDLTKSALRELKTVSAD AAS22117.1 QLAREEQIENPRQSRFVLGAIALGVATAAAVTAGIAIAKTIRLE SEVNAIKGALKQTNEAVSTLGNGVRVLATAVRELKEFVSKNL TSAINRNKCDIADLKMAVSFSQFNRRFLNVVRQFSDNAGITP AISLDLMTDAELARAVSYMPTSAGQIKLMLENRAMVRRKGFG ILIGVYGSSVIYMVQLPIFGVIDTPCWIIKAAPSCSEKNGNYAC LLREDQGWYCKNAGSTVYYPNEKDCETRGDHVFCDTAAGIN VAEQSRECNINISTTNYPCKVSTGRHPISMVALSPLGALVACY KGVSCSIGSNRVGIIKQLPKGCSYITNQDADTVTIDNTVYQLS KVEGEQHVIKGRPVSSSFDPIRFPEDQFNVALDQVFESIENS QALVEQSNKILNSAEKGNTGFIIVIILVAVLGLTMISVSIIIIIKKTR KPTGAPPELNGVTNGGFIPHS HR18786-11 6 MSWKVMIIISLLITPQHGLKESYLEESCSTITEGYLSVLRTGWY (B2) / TNVFTLEVGDVENLTCTDGPSLIKTELDLTKSALRELKTVSAD ANW37992.1 QLAREEQIENPRQSRFVLGAIALGVATAAAVTAGIAIAKTIRLE SEVNAIKGALKTTNEAVSTLGNGVRVLATAVRELKEFVSKNLT SAINKNKCDIADLKMAVSFSQFNRRFLNVVRQFSDNAGITPAI SLDLMNDAELARAVSYMPTSAGQIKLMLENRAMVRRKGFGIL IGVYGSSVIYMVQLPIFGVINTPCWIIKAAPSCSEKDGNYACLL REDQGWYCKNAGSTVYYPNEKDCETRGDHVFCDTAAGINV AEQSRECNINISTTNYPCKVSTGRHPISMVALSPLGALVACYK GVSCSTGSNQVGIIKQLPKGCSYITNQDADTVTIDNTVYQLSK VEGEQHVIKGRPVSNSFDPIRFPEDQFNVALDQVFESIENSQ ALVDQSNKILNSAEKGNTGFIIVIILIAVLGLTMISVSIIIIIKKTRKP AGAPPELNGVTNGGFIPHS 6073-B2 (B2) / 7 MSWKVMIIISLLITPQHGLKESYLEESCSTITEGYLSVLRTGWY QDA18370.1 TNVFTLEVGDVENLTCTDGPSLIKTELDLTKSALRELKTVSAD QLAREEQIENPRQSRFVLGAIALGVATAAAVTAGIAIAKTIRLE SEVNAIKGALKTTNEAVSTLGNGVRVLATAVRELKEFVSKNLT SAINKNKCDIADLKMAVSFSQFNRRFLNVVRQFSDNAGITPAI SLDLMNDAELARAVSYMPTSAGQIKLMLENRAMVRRKGFGIL IGVYGSSVIYMVQLPIFGVINTPCWIIKAAPSCSEKDGNYACLL REDQGWYCKNAGSTVYYPNEKDCETRGDHVFCDTAAGINV AEQSRECNINISTTNYPCKVSTGRHPISMVALSPLGALVACYK GVSCSIGSNQVGIIKQLPKGCSYITNQDADTVTIDNTVYQLSK VEGEQHVIKGRPVSNSFDPIRFPEDQFNVALDQVFESIENSQ ALVDQSNKILNSAEKGNTGFIIVIILIAVLGLTMISVSIIIIIKKTRKP AGAPPELNGVTNGGFIPHS 3. Nucleic Acids Encoding hMPV F Protein Mutants In another aspect, the present invention provides nucleic acid that encode a hMPV F protein mutant described herein above. These nucleic acids include DNA, cDNA, and RNA sequences. Nucleic acids that encode only a F2 polypeptide or only a F1 polypeptide of a hMPV F mutant are also encompassed by the invention. The nucleic acid can be incorporated into a vector, such as an expression vector. In some embodiments, the nucleic acid encodes a precursor F0 polypeptide that, when expressed in an appropriate cell, is processed into a disclosed hMPV F mutant. In some embodiments, the nucleic acid encodes a precursor F0 polypeptide that, when expressed in an appropriate cell, is processed into a disclosed hMPV F mutant, wherein the precursor F0 polypeptide includes, from N- to C- terminus, a signal peptide, a F2 polypeptide, and a F1 polypeptide. In some embodiments, the signal peptide comprises the amino acid sequence set forth as positions 1-18 of any one SEQ ID NOs: 1 to 7, wherein the amino acid positions correspond to the amino acid sequence of a reference of SEQ ID NO:1. In a preferred embodiment, the nucleic acid is an RNA, more preferably an mRNA. In a preferred embodiment, the mRNA encodes a precursor F0 polypeptide that, when expressed in an appropriate cell, is processed into a full lenght hMPV F protein mutant disclosed herein (i.e comprising one or more mutations, a full lenght F1 polypeptide and a full lenght F2 polypeptide). A full-length F1 polypeptide of the hMPV F mutants corresponds to amino acid positions 103-539 of the native hMPV F0 precursor, and includes (from N- to C-terminus) an extracellular region (residues 103 to 489), a transmembrane domain (residues 490-514), and a cytoplasmic domain (residues 515-539). In a preferred embodiment, the nucleic acid is an mRNA comprising a chemically modified nucleotide. In a preferred embodiment, the nucleic acid is an mRNA comprising N1-methylpseudouridine. Preferably, all the uridines of the mRNA are replaced by N1-methylpseudouridine. In some specific embodiments, the present disclosure provides a nucleic acid which encodes a mutant comprising engineered interprotomer disulfide mutations selected from the group consisting of : (1) 69C and 195C; (2) 80C and 224C; (3) 211C and 250C; (4) 337C and 423C, (5) 111C and 323C; (6) 69C, 195C, 80C and 224C; (7) 69C, 195C, 211C and 250C; (8) 69C, 195C, 337C and 423C; (9) 69C, 195C, 111C and 323C; (10) 80C, 224C, 211C and 250C; (11) 80C, 224C, 337C and 423C; (12) 80C, 224C, 111C and 323C; (13) 211C, 250C, 337C and 423C; (14) 211C, 250C, 111C and 323C; (15) 337C, 423C, 111C and 323C; (16) 69C, 195C, 80C, 224C, 211C and 250C; (17) 69C, 195C, 80C, 224C, 337C and 423C; (18) 69C, 195C, 80C, 224C, 111C and 323C; (19) 69C, 195C, 211C, 250C, 337C and 423C; (20) 69C, 195C, 211C, 250C, 111C and 323C; (21) 69C, 195C, 337C, 423C, 111C and 323C; (22) 80C, 224C, 211C, 250C, 337C and 423C; (23) 80C, 224C, 211C, 250C, 111C and 323C; (24) 80C, 224C, 337C, 423C, 111C and 323C; and, (25) 211C, 250C, 337C, 423C, 111C and 323C. In some specific embodiments, the present disclosure provides a nucleic acid, preferably a mRNA, more preferably a mRNA wherein all the uridines are replaced by N1- methylpseudouridine, said nucleic acid encoding a precursor F0 polypeptide that, when expressed in an appropriate cell, is processed into a full lenght hMPV F protein mutant disclosed herein comprising the mutations selected from the group consisting of : (1) 69C and 195C; (2) 80C and 224C; (3) 211C and 250C; (4) 337C and 423C, (5) 111C and 323C; (6) 69C, 195C, 80C and 224C; (7) 69C, 195C, 211C and 250C; (8) 69C, 195C, 337C and 423C; (9) 69C, 195C, 111C and 323C; (10) 80C, 224C, 211C and 250C; (11) 80C, 224C, 337C and 423C; (12) 80C, 224C, 111C and 323C; (13) 211C, 250C, 337C and 423C; (14) 211C, 250C, 111C and 323C; (15) 337C, 423C, 111C and 323C; (16) 69C, 195C, 80C, 224C, 211C and 250C; (17) 69C, 195C, 80C, 224C, 337C and 423C; (18) 69C, 195C, 80C, 224C, 111C and 323C; (19) 69C, 195C, 211C, 250C, 337C and 423C; (20) 69C, 195C, 211C, 250C, 111C and 323C; (21) 69C, 195C, 337C, 423C, 111C and 323C; (22) 80C, 224C, 211C, 250C, 337C and 423C; (23) 80C, 224C, 211C, 250C, 111C and 323C; (24) 80C, 224C, 337C, 423C, 111C and 323C; and, (25) 211C, 250C, 337C, 423C, 111C and 323C. C. Immunogenic Compositions Comprising a hMPV F protein mutant or a Nucleic Acid Encoding a hMPV F Protein Mutant In another aspect, the invention provides immunogenic compositions that comprise a hMPV F protein mutant as disclosed herein or a nucleic acid, preferably mRNA, or vector encoding such a hMPV F protein mutant. In some embodiments, the immunogenic composition comprises a hMPV A F protein mutant or a nucleic acid encoding a hMPV A F protein mutant as disclosed herein. In some embodiments, the immunogenic composition comprises a hMPV B F protein mutant or a nucleic acid encoding a hMPV B F protein mutant as disclosed herein. In some embodiments, the immunogenic composition comprises a hMPV A F protein mutant or a nucleic acid encoding a hMPV A F protein mutant as disclosed herein and a hMPV B F protein mutant or a nucleic acid encoding a hMPV B F protein mutant as disclosed herein. In one preferred embodiment,the immunogenic composition a nucleic acid encoding a hMPV B F protein mutant as disclosed herein. The immunogenic composition of the present invention may further comprise additional antigens such as: (1) a PIV1 F protein mutant or a nucleic acid encoding a PIV1 F protein mutant, and/or, (2) a PIV3 F protein mutant or a nucleic acid encoding a PIV3 F protein mutant, and/or (3) a RSV A F protein mutant or a nucleic acid encoding a RSV F protein mutant and/or (4) a RSV B F protein mutant or a nucleic acid encoding a RSV F protein mutant. 1. EXAMPLES OF PIV1 F PROTEIN MUTANT OR NUCLEIC ACID ENCODING A PIV1 F PROTEIN MUTANT THAT CAN BE INCLUDED IN THE IMMUNOGENIC COMPOSITION OF THE PRESENT INVENTION. In some embodiments, the immunogenic composition of the present invention comprises a PIV1 F protein mutant or a nucleic acid encoding a PIV1 F protein mutant. In some embodiments, the immunogenic composition of the present invention comprises a PIV1 F protein mutant or a nucleic acid encoding a PIV1 F protein mutant disclosed in the following embodiments. E1. A mutant of a wild-type PIV1 F protein, which mutant comprises a F1 polypeptide and a F2 polypeptide, wherein the mutant comprises at least one amino acid mutation relative to the amino acid sequence of the wild-type PIV1 F protein, and wherein the amino acid mutation is selected from the group consisting of: (1) at least one engineered disulfide bond mutation; (2) at least one cavity filling mutation; (3) at least one proline substitution mutation; (4) at least one glycine replacement mutation; (5) a cleavage site mutation; (6) a combination of at least one engineered disulfide mutation and at least one cavity filling mutation; (7) a combination of at least one engineered disulfide mutation and at least one proline substitution mutation; (8) a combination of at least one engineered disulfide mutation and a least one glycine replacement mutation; (8) a combination of at least one engineered disulfide mutation, at least one cavity filling mutation and at least one proline substitution mutation; (10) a combination of at least one engineered disulfide mutation, at least one cavity filling mutation, and a least one glycine replacement mutation; (11) a combination of at least one engineered disulfide mutation, at least one proline substitution mutation and a least one glycine replacement mutation; (12) a combination of at least one engineered disulfide mutation, at least one cavity filling mutation, at least one proline substitution mutation and a least one glycine replacement mutation (13) a combination of a cleavage site mutation and at least one engineered disulfide mutation; (14) a combination of a cleavage site mutation and at least one cavity filling mutation; (15) a combination of a cleavage site mutation and at least one proline substitution mutation; (16) a combination of a cleavage site mutation and at least one glycine replacement mutation; (17) a combination of a cleavage site mutation and at least one engineered disulfide mutation and at least one cavity filling mutation; (18) a combination of a cleavage site mutation and at least one engineered disulfide mutation and at least one proline substitution mutation; (19) a combination of a cleavage site mutation and at least one engineered disulfide mutation and a least one glycine replacement mutation; (20) a combination of a cleavage site mutation, at least one engineered disulfide mutation, at least one cavity filling mutation and at least one proline substitution mutation; (21) a combination of a cleavage site mutation, at least one engineered disulfide mutation, at least one cavity filling mutation, and a least one glycine replacement mutation; (22) a combination of a cleavage site mutation,at least one engineered disulfide mutation, at least one proline substitution mutation and a least one glycine replacement mutation; (23) a combination of a cleavage site mutation, at least one engineered disulfide mutation, at least one cavity filling mutation, at least one proline substitution mutation and a least one glycine replacement mutation; (24) a combination of a cleavage site mutation, at least one cavity filling mutation and at least one proline substitution mutation; (25) a combination of a cleavage site mutation, at least one cavity filling mutation and a least one glycine replacement mutation; (26) a combination of a cleavage site mutation, at least one proline substitution mutation and at least one glycine replacement mutation; (27) a combination of at least one cavity filling mutation and at least one proline substitution mutation; (28) a combination of at least one cavity filling mutation and a least one glycine replacement mutation (29) a combination of at least one proline substitution mutation and a least one glycine replacement mutation: (30) a combination of at least one cavity filling mutation, at least one proline substitution mutation and a least one glycine replacement mutation. E2. The mutant according to E1 wherein the mutant comprises an engineered disulfide mutation. E3. The mutant according to E1 or E2 wherein the engineered disulfide mutation is Q92C- G134C. E4. The mutant according to any one of E1 to E3, wherein the mutant comprises a cavity filling mutation. E5. The mutant according to any one of E1 to E4, wherein the cavity filling mutation is selected from T198A, Q92A, Q92L, A466L, A466V, A466I, S473V, S473L, S473I, S473A, A480L and A480V. E6. The mutant according to E5, wherein the cavity filling mutation is T198A. E7. The mutant according to E5, wherein the cavity filling mutation is Q92A. E8. The mutant according to E5, wherein the cavity filling mutation is Q92L. E9. The mutant according to E5, wherein the cavity filling mutation is A466L. E10. The mutant according to E5, wherein the cavity filling mutation is A466V. E11. The mutant according to E5, wherein the cavity filling mutation is S473V. E12. The mutant according to E5, wherein the cavity filling mutation is S473L. E13. The mutant according to E5, wherein the cavity filling mutation is S473I. E14. The mutant according to E5, wherein the cavity filling mutation is S473A. E15. The mutant according to E5, wherein the cavity filling mutation is A480L. E16. The mutant according to E5, wherein the cavity filling mutation is A480V. E17. The mutant according to any one of E1 to E4, wherein the mutant comprises two or three cavity filling mutations selected from T198A, Q92A, Q92L, A466L, A466V, A466I, S473V, S473L, S473I, S473A, A480L and A480V. E18. The mutant according to E17, wherein the cavity filling mutations are A466L and S473L. E19. The mutant according to E17, wherein the cavity filling mutations are A466I and S473I. E20. The mutant according to any one of E18 or E19 further comprising the cavity filling mutation A480L or A480V. E21. The mutant according to any one of E1 to E20, wherein the mutant comprises a proline substitution mutation. E22. The mutant according to E21, wherein the proline substitution mutation is A128P. E23. The mutant according to any one of E1 to E22, wherein the mutant comprises a glycine replacement mutation. E24. The mutant according to E23, wherein the glycine replacement mutation is G134A or G134L. E25. The mutant according to E24, wherein the glycine replacement mutation is G134A. E26. The mutant according to any one of E1 to E25, wherein the mutant comprises a cleavage site mutation. E27. The mutant according to E26, wherein the cleavage site mutation is F113G and F114S. E28. The mutant according to E1, wherein the mutant comprises the mutations selected from from the group consisting of: (1) Q92C-G134C; (2) A466L; (3) A466V; (4) S473V; (5) S473L; (6) A480L; (7) A466L and S473A; (8) A466L and S473L; (9) T198A; (10) G134A; (11) A128P; (12) F113G, F114S, Q92C-G134C, A466L, S473L and A480L; (13) Q92C-G134C, A466L, S473L and A480L; (14) Q92C-G134C, A466L and S473L; (15) F113G, F114S, Q92C-G134C, A466V, S473V and A480V; (16) Q92C-G134C, A466V, S473V and A480V; (17) Q92C-G134C, A466V and S473V; (18) F113G, F114S, A466L, S473L, A480L and G134A; (19) A466L, S473L, A480L and G134A; (20) A466L, S473L and G134A; (21) F113G, F114S, A466L, S473L, A480L, Q92A and G134A; (22) F113G, F114S, A466L, S473L and G134A; (23) A466L, S473L, A480L, Q92A, G134A; (24) A466L, S473L, Q92A, G134A; (25) F113G, F114S, Q92L, G134A; (26) A466L, S473L, A480L, Q92L and G134A; (27) A466L, S473L, Q92L and G134A; (28) F113G, F114S, A466L, S473L, A480L, Q92A and G134L; (29) A466L, S473L, A480L, Q92A and G134L; (30) F113G, F114S, Q92C-G134C, A466I, S473I and A480L; (31) F113G, F114S, Q92C-G134C, A466I and, S473I; and, (32) A466I, S473I, A480L, Q92L and G134A. E29. The mutant according to E1, wherein the mutant comprises the mutations A466L, S473L, A480L and G134A. E30. The mutant according to E1, wherein the mutant comprises the mutations F113G, F114S, A466L, S473L and G134A. E31. The mutant according to E1, wherein the mutant comprises the mutations F113G, F114S, A466L, S473L, A480L and G134A. E32. The mutant according to E1, wherein the mutant comprises the mutations F113G, F114S, Q92C-G134C, A466L, S473L and A480L. E33. The mutant according to any one of E1 to E32, wherein the F1 polypeptide lacks the entire cytoplasmic domain or the F1 polypeptide lacks the cytoplasmic domain and a portion of or all entire transmembrane domain. Preferably, the F1 polypeptide lacks the cytoplasmic domain and the transmembrane domain. Preferably, the F1 polypeptide comprises or consists of amino acid residues 113 to 477. Preferably, the F1 polypeptide comprises or consists of amino acid residues 113 to 480. E34. The mutant according to any one of E1 to E31, wherein the F1 polypeptide comprises the ectodomain, the transmembrane domain and the cytoplasmic domain. In a preferred embodiment, the mutant comprises the full length F1 polypeptide and the full length F2 polypeptide. E35. The mutant according to any one of E1 to E34, wherein the mutant is linked to a trimerization domain. E36. The mutant according to E35, wherein the trimerization domain is a GCN4 leucine zipper or a phage T4 fibritin foldon. E37. The mutant according to E36, wherein the trimerization domain is a phage T4 fibritin foldon. E38. The mutant according to E37, wherein the trimerization domain is a phage T4 fibritin foldon of SEQ ID NO.7. E39. The mutant according to any one of E35 to E38, wherein the trimerization domain is linked to the C-terminus of the F1 polypeptide. E40. The mutant according to any one of E35 to E39, wherein the trimerization domain is linked to the C-terminus of the F1 polypeptide via a linker. E41. The mutant according to E40, wherein the trimerization domain is linked to the C-terminus of the F1 polypeptide via a linker selected from the group consisting of GG, GS, GGGS or SAIG. E42. The mutant according to E41, wherein the linker is GGGS. E43. The mutant according to any one of E1 to E42, wherein the mutant is in the form of a trimer. E44. The mutant according to any one of E1 to E43, wherein the mutant is in the prefusion conformation. E45. The mutant of any one of E1 to E44 wherein the wild-type PIV1 F protein is SEQ ID NO:37. E46. The mutant of any one of E1 to E45 wherein the amino acid positions correspond to the amino acid sequence of a reference of SEQ ID NO:37. E47. A nucleic acid comprising at least one coding sequence encoding at least one mutant of a wild-type PIV 1 F protein according to any one of embodiments E1-E46, preferably E34, or an immunogenic fragment or immunogenic variant thereof, wherein the nucleic acid comprises at least one heterologous untranslated region (UTR). E48. A nucleic acid according to any one of the preceding embodiments, wherein the at least one heterologous untranslated region is selected from at least one heterologous 5’- UTR and/or at least one heterologous 3’-UTR. E49. A nucleic acid according to any one of the preceding embodiments, wherein the at least one heterologous 3’-UTR comprises or consists of a nucleic acid sequence having at least, at most, exactly, or between any two of 99%, 98%, 97%, 96%, 95%, 90%, 85%, or 80% identity to CΨCGAGCΨGGΨ ACΨGCAΨGCA CGCAAΨGCΨA GCΨGCCCCΨΨ ΨCCCGΨCCΨG GGΨACCCCGA GΨCΨCCCCCG ACCΨCGGGΨC CCAGGΨAΨGC ΨCCCACCΨCC ACCΨGCCCCA CΨCACCACCΨ CΨGCΨAGΨΨC CAGACACCΨC CCAAGCACGC AGCAAΨGCAG CΨCAAAACGC ΨΨAGCCΨAGC CACACCCCCA CGGGAAACAG CAGΨGAΨΨAA CCΨΨΨAGCAA ΨAAACGAAAG ΨΨΨAACΨAAG CΨAΨACΨAAC CCCAGGGΨΨG GΨCAAΨΨΨCG ΨGCCAGCCAC ACCCΨGGAGC ΨAGC. E50. A nucleic acid according to any one of the preceding embodiments, wherein the at least one heterologous 5’-UTR comprises or consists of a nucleic acid sequence having at least, at most, exactly, or between any two of 99%, 98%, 97%, 96%, 95%, 90%, 85%, or 80% identity to GAAΨAAAC ΨAGΨAΨΨCΨΨ CΨGGΨCCCCA CAGACΨCAGA GAGAACCCGC CACC. E51. A nucleic acid according to any one of the preceding embodiments, wherein the nucleic acid comprises at least one poly(A) sequence, preferably comprising 30 to 200 adenosine nucleotides and/or at least one poly(C) sequence, preferably comprising 10 to 40 cytosine nucleotides. E52. A nucleic acid according to any one of the preceding embodiments, wherein the nucleic acid is a DNA or an RNA. E53. A nucleic acid according to any one of the preceding embodiments, wherein the nucleic acid is a coding RNA. E54. A nucleic acid according to E63, wherein the coding RNA is an mRNA, a self-replicating RNA, a circular RNA, or a replicon RNA. E55. A nucleic acid according to any one of the preceding embodiments, wherein the nucleic acid, preferably the coding RNA, is an mRNA. E56. A nucleic acid according to E55, wherein the mRNA is not a replicon RNA or a self- replicating RNA. E57. A nucleic acid according to any one of the preceding embodiments E55- E56, wherein the mRNA comprises at least one poly(A) sequence comprising 30 to 200 adenosine nucleotides and the 3’ terminal nucleotide is an adenosine. E58. A nucleic acid according to any one of the preceding embodiments E52 – E57, wherein the RNA, preferably the coding RNA, comprises a 5’-cap structure, preferably m7G, capO, cap1 , cap2, a modified capO or a modified cap1 structure, preferably a 5’- cap1 structure. E59. A nucleic acid according to any one of the preceding embodiments E52 – E58, wherein the RNA is codon-optimized. E60. A nucleic acid according to any one of the preceding embodiments E52 – E59, wherein the RNA comprises a chemically modified nucleotide. E61. A nucleic acid according to any one of the preceding embodiments E52 – E60, wherein the RNA comprises N1-methylpseudouridine substitution. Preferably, all the uridines of the RNA are replaced by N1-methylpseudouridine. E62. A nucleic acid according to any one of the preceding embodiments E52 – E61, wherein the RNA is a purified RNA, preferably an RNA that has been purified by RP-HPLC and/or TFF. E63. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E47 – E62. E64. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E47 – E62, wherein the composition comprises at least one pharmaceutically acceptable carrier. E65. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E47 – E62, wherein the composition is a multivalent composition comprising a plurality or at least more than one of the nucleic acid according to any one of E47 – E62. E66. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E47 – E62, wherein the composition comprises RNA with an RNA integrity of 70% or more. E67. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E47 – E62, wherein the composition comprises RNA with a capping degree of 70% or more, preferably wherein at least 70%, 80%, or 90% of the mRNA species comprise a Cap1 structure. E68. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E47 – E62, wherein the at least one nucleic acid is complexed or associated with or at least partially complexed or partially associated with one or more cationic or polycationic compound, preferably cationic or polycationic polymer, cationic or polycationic polysaccharide, cationic or polycationic lipid, cationic or polycationic protein, cationic or polycationic peptide, or any combinations thereof. E69. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E47 – E62, wherein the at least one nucleic acid is complexed or associated with one or more lipids or lipid-based carriers, thereby forming liposomes, lipid nanoparticles (LNP), lipoplexes, and/or nanoliposomes, preferably encapsulating the at least one nucleic acid. E70. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E47 – E62, wherein the at least one nucleic acid is complexed with one or more lipids thereby forming lipid nanoparticles. E71. A composition according to any one of the preceding embodiments E80 – E81 , wherein the LNP comprises a cationic lipid according to formula III-3: E72. A composition according to any one of the preceding embodiments E69 -E71, wherein the LNP comprises a PEG lipid of formula (IVa): E73. A composition according to embodiment E72, wherein n has a mean value ranging from 30 to 60, preferably wherein n has a mean value of about 45, 46, 47, 48, 49, 50, 51 , 52, 53, 54, most preferably wherein n has a mean value of 49 or 45. E74. A composition according to any one of the preceding embodiments E69 -E73, wherein the LNP comprises a PEG lipid of formula (IVa): wherein n is an integer selected such that the average molecular weight of the PEG lipid is about 2500g/mol. E75. A composition according to any one of the preceding embodiments E69 -E74, wherein the LNP comprises one or more neutral lipids and/or one or more steroid or steroid analogues. E76. A composition according to any one of the preceding embodiments E69 -E75, wherein the neutral lipid is 1 ,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), preferably wherein the molar ratio of the cationic lipid to DSPC is in the range from about 2:1 to about 8:1. E77. A composition according to any one of the preceding embodiments E69 -E76, wherein the steroid is cholesterol, preferably wherein the molar ratio of the cationic lipid to cholesterol is in the range from about 2:1 to about 1:1. E78. A composition according to any one of the preceding embodiments E69 -E77, wherein the LNP comprises (i) at least one cationic lipid, preferably a lipid of formula (III), more preferably lipid Ill-3; (ii) at least one neutral lipid, preferably 1 ,2-distearoyl-sn-glycero-3- phosphocholine (DSPC); (iii) at least one steroid or steroid analogue, preferably cholesterol; and (iv) at least one polymer conjugated lipid, preferably a PEG-lipid derived from formula (IVa, with n = 49), wherein (i) to (iv) are in a molar ratio of about 20-60% cationic lipid, 5-25% neutral lipid, 25-55% sterol, and 0.5-15% PEG-lipid. E79. A composition according to any one of the preceding embodiments E69 -E78, wherein the LNP comprises (i) at least one cationic lipid, preferably a lipid of formula (III), more preferably lipid Ill-3; (ii) at least one neutral lipid, preferably 1 ,2-distearoyl-sn-glycero-3- phosphocholine (DSPC); (iii) at least one steroid or steroid analogue, preferably cholesterol; and (iv) at least one polymer conjugated lipid, preferably a PEG-lipid derived from formula (IVa, with n = 45), wherein (i) to (iv) are in a molar ratio of about 20-60% cationic lipid, 5-25% neutral lipid, 25-55% sterol, and 0.5-15% PEG-lipid. E80. A composition according to any one of the preceding embodiments E69 -E79, wherein (i) to (iv) are in a molar ratio of about 50:10:38.5:1.5, preferably 47.5:10:40.8:1.7 or more preferably 47.4:10:40.9:1.7. E81. A composition according to any one of the preceding embodiments E69 -E80, wherein the nucleic acid is RNA and the composition comprises less than about 20% free (non complexed or non-encapsulated) RNA, preferably less than about 15% free RNA, more preferably less than about 10% free RNA. E82. A composition according to any one of the preceding embodiments E69 -E81, wherein the wt/wt ratio of lipid to nucleic acid is from about 10:1 to about 60:1 , preferably from about 20:1 to about 30:1 , for example about 25:1. E83. A composition according to any one of the preceding embodiments E69 -E82, wherein the n/p ratio of the LNPs encapsulating the nucleic acid is in a range from about 1 to about 10, preferably in a range from about 5 to about 7, more preferably about 6. E84. A composition according to any one of the preceding embodiments E69 -E83, wherein the composition has a polydispersity index (PDI) value of less than about 0.4, preferably of less than about 0.3, more preferably of less than about 0.2, most preferably of less than about 0.1. E85. A composition compris according to any one of the preceding embodiments E69 -E84, wherein the LNPs have a Z-average size in a range of about 60nm to about 120nm, preferably less than about 120nm, more preferably less than about 100nm, most preferably less than about 80nm. E86. A composition according to any one of the preceding embodiments E69 -E85, wherein the LNPs comprise less than about 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1% LNPs that have a particle size exceeding about 500nm. E87. A composition according to any one of the preceding embodiments E69 -E86, wherein the LNPs comprise less than about 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1% LNPs that have a particle size smaller than about 20nm. E88. A composition according to any one of the preceding embodiments E69 -E87, wherein the LNP comprises (i) at least one cationic lipid; (ii) at least one neutral lipid; (iii) at least one steroid or steroid analogue; and (iv) at least one PEG-lipid, wherein (i) to (iv) are in a molar ratio of about 20-60% cationic lipid, 5-25% neutral lipid, 25-55% sterol, and 0.5-15% PEG-lipid. E89. A composition according to any one of the preceding embodiments E69 -E88, wherein the LNP comprises (i) at least one cationic lipid according to formula III-3; (ii) DSPC; (iii) cholesterol; and (iv) a PEG-lipid, according to formula IVa, wherein (i) to (iv) are in a molar ratio of about 20-60% cationic lipid, 5-25% neutral lipid, 25-55% sterol, and 0.5-15% PEG-lipid. E90. A composition according to any one of the preceding embodiments E63-E89, wherein the composition is a lyophilized composition. 2. EXAMPLES OF PIV3 F PROTEIN MUTANT OR NUCLEIC ACID ENCODING A PIV3 F PROTEIN MUTANT THAT CAN BE INCLUDED IN THE IMMUNOGENIC COMPOSITION OF THE PRESENT INVENTION. In some embodiments, the immunogenic composition of the present invention comprises a PIV3 F protein mutant or a nucleic acid encoding a PIV3 F protein mutant. In some embodiments, the immunogenic composition of the present invention comprises a PIV3 F protein mutant or a nucleic acid encoding a PIV3 F protein mutant disclosed in the following embodiments. E1. A mutant of a wild-type PIV3 F protein, which mutant comprises a F1 polypeptide and a F2 polypeptide, wherein the mutant comprises at least one amino acid mutation relative to the amino acid sequence of the wild-type PIV3 F protein, and wherein the amino acid mutation is selected from the group consisting of: (1) at least one engineered disulfide bond mutation; (2) at least one cavity filling mutation; (3) at least one proline substitution mutation; (4) at least one glycine replacement mutation; (5) an electrostatic mutation (6) a combination of at least one engineered disulfide mutation and at least one cavity filling mutation; (7) a combination of at least one engineered disulfide mutation and at least one proline substitution mutation; (8) a combination of at least one engineered disulfide mutation and a least one glycine replacement mutation; (8) a combination of at least one engineered disulfide mutation, at least one cavity filling mutation and at least one proline substitution mutation; (10) a combination of at least one engineered disulfide mutation, at least one cavity filling mutation, and a least one glycine replacement mutation; (11) a combination of at least one engineered disulfide mutation, at least one proline substitution mutation and a least one glycine replacement mutation; (12) a combination of at least one engineered disulfide mutation, at least one cavity filling mutation, at least one proline substitution mutation and a least one glycine replacement mutation (13) a combination of an electrostatic mutation and at least one engineered disulfide mutation; (14) a combination of an electrostatic mutation and at least one cavity filling mutation; (15) a combination of an electrostatic mutation and at least one proline substitution mutation; (16) a combination of an electrostatic mutation and at least one glycine replacement mutation; (17) a combination of an electrostatic mutation and at least one engineered disulfide mutation and at least one cavity filling mutation; (18) a combination of an electrostatic mutation and at least one engineered disulfide mutation and at least one proline substitution mutation; (19) a combination of an electrostatic mutation and at least one engineered disulfide mutation and a least one glycine replacement mutation; (20) a combination of an electrostatic mutation and at least one engineered disulfide mutation, at least one cavity filling mutation and at least one proline substitution mutation; (21) a combination of an electrostatic mutation and at least one engineered disulfide mutation, at least one cavity filling mutation, and a least one glycine replacement mutation; (22) a combination of an electrostatic mutation and at least one engineered disulfide mutation, at least one proline substitution mutation and a least one glycine replacement mutation; (23) a combination of an electrostatic mutation and at least one engineered disulfide mutation, at least one cavity filling mutation, at least one proline substitution mutation and a least one glycine replacement mutation; (24) a combination of an electrostatic mutation, at least one cavity filling mutation and at least one proline substitution mutation; (25) a combination of an electrostatic mutation, at least one cavity filling mutation and a least one glycine replacement mutation; (26) a combination of an electrostatic mutation, at least one proline substitution mutation and at least one glycine replacement mutation; (27) a cleavage site mutation, and, (28) a cleavage site mutation in combination with the mutation or combination of mutations listed in above items (1) to (26). E2. The mutant according to E1 wherein the mutant comprises an engineered disulfide mutation selected from the group consisting of V175C-A202C, S160C-V170C, E209C- L234C, E209C-S233C, G85C-E209C and Q162C-L168C. E3. The mutant according to E2 wherein the engineered disulfide mutation is V175C-A202C or Q162C-L168C. E4. The mutant according to E2 wherein the engineered disulfide mutation is S160C-V170C. E5. The mutant according to E2 wherein the engineered disulfide mutation is E209C-L234C. E6. The mutant according to E2 wherein the mutant comprises two engineered disulfide mutations selected from the group consisting of V175C-A202C, S160C-V170C, E209C- L234C and Q162C-L168C, preferably S160C-V170C and E209C-L234C. E7. The mutant according to any one of E1 to E6, wherein the mutant comprises a cavity filling mutation. E8. The mutant according to E7, wherein the cavity filling mutation is selected from the group consisting of T277V, S470A, S470L, S477A, A463L, I474F and I474Y. E9. The mutant according to E7, wherein the cavity filling mutation is selected from the group consisting of S470A, I474F S477A and A463L. E10. The mutant according to E8, wherein the cavity filling mutation is S470A or S470L. E11. The mutant according to E8, wherein the cavity filling mutation is S477A. E12. The mutant according to E8, wherein the cavity filling mutation is A463L. E13. The mutant according to E4, wherein the cavity filling mutation is I474Y or I474F. E14. The mutant according to any one of E1 to E13, wherein the mutant comprises two or three cavity filling mutations selected from S470A, S470L, S477A, A463L, I474F and I474Y. E15. The mutant according to E14, wherein the cavity filling mutations are S470A and S477A. E16. The mutant according to E14, wherein the cavity filling mutations are A463L and I474F, A463L and S470L or, A463L and I474F. E17. The mutant according to any one of E1 to E16, wherein the mutant comprises a proline substitution mutation. E18. The mutant according to E17, wherein the proline substitution mutation is S164P or G219P. E19. The mutant according to any one of E1 to E18, wherein the mutant comprises a cleavage site mutation. E20. The mutant according to E19, wherein the cleavage site mutation comprises F110G and F111S. E21. The mutant according to any one of E1 to E20, wherein the mutant comprises a glycine replacement mutation. E22. The mutant according to E21, wherein the glycine replacement mutation is G196A or G230A. E23. The mutant according to E21, wherein the glycine replacement mutation is G196A. E24. The mutant according to E21, wherein the glycine replacement mutation is G230A. E25. The mutant according to any one of E1 to E24, wherein the mutant comprises an electrostatic mutation. E26. The mutant according to E25, wherein the electrostatic mutation is E182L or D455S. E27. The mutant according to E1, wherein the mutant comprises the mutations selected from the group consisting of: (1) V175C and A202C; (2) S160C and V170C; (3) S164P; (4) G196A; (5) G219P; (6) G230A; (7) E182L; (8) S470A; (9) S477A; (10) S470A and S477A; (11) D455S; (12) A463L; (13) Q162C, L168C, S470A and S477A; (14) S160C, V170C, S470A and S477A; (15) G230A, S470A and S477A; (16) A463L, S470A and S477A; (17) E209C and L234C; (18) A463L and S470L; (19) S160C, V170C, E209C, L234C, A463L and S470L; (20) S160C, V170C, E209C, L234C, A463L and I474F; (21) S160C, V170C, E209C, L234C, A463L, S470L, F110G, F111S; (22) S160C, V170C, A463L and S470L; (23) Q162C, L168C, G230A, A463V and I474Y; (24) Q162C, L168C, G230A, S470A and S477A; (25) Q162C, L168C, G230A and A463L; (26) Q162C, L168C, G230A, A463L, S470A and S477A; (27) S160C, V170C, G230A, A463V and I474Y; (28) S160C, V170C, G230A, S470A and S477A; (29) S160C, V170C, G230A and A463L; (30) S160C, V170C, G230A, A463L, S470A and S477A; (31) S160C, V170C and A463L; (32) E209C andS233C; (33) G85C and E209C; (34) T277V; (35) A463L and I474F; (36) A463I, S470I (37) S160C, V170C, E209C, S233C, A463L and S470L; (38) S160C, V170C, E209C, S233C, A463L and I474F; (39) S160C, V170C, G85C, E209C, A463L and S470L; (40) S160C, V170C, G85C, E209C, A463L and I474F; (41) S160C, V170C, E209C, L234C, T277V, A463L and S470L; (42) S160C, V170C, E209C, L234C, T277V, A463L and I474F; (43) S160C, V170C, E209C, S233C, T277V, A463L and S470L; (44) S160C, V170C, E209C, S233C, T277V, A463L and I474F; (45) S160C, V170C, G85C, E209C, T277V, A463L and I474F; (46) S160C, V170C, E209C, L234C, D455S, A463L and S470L; (47) S160C, V170C, E209C, S233C, D455S, A463Land S470L; (48) S160C, V170C, G85C, E209C, D455S, A463L and S470L; (49) S160C, V170C, E209C, L234C, T277V, D455S, A463L and S470L; (50) S160C, V170C, E209C, S233C, T277V, D455S, A463L and S470L; (51) S160C, V170C, G85C, E209C, T277V, D455S, A463L and S470L; (52) S160C, V170C and S470L; (53) R106G, T107S, E108A, R109S, S160C, V170C, E209C, L234C, A463L and S470L; (54) R106G, T107S, E108A, R109S, S160C, V170C, E209C, S233C, A463L and S470L; (55) R106G, T107S, E108A, R109S, S160C, V170C, G85C, E209C, A463L and S470L; (56) F110G, F111S, S160C, V170C, E209C, L234C, A463L and S470L; (57) F110G, F111S, S160C, V170C, E209C, S233C, A463L and S470L; (58) F110G, F111S, S160C, V170C, A463L and S470L; (59) F110G, F111S, S160C, V170C and S470L; (60) S160C, V170C, A463L and S477L; (61) S160C, V170C, E209C, L234C, A463L and S470L; and, (62) S160C, V170C and S470L. E28. The mutant according to E1, wherein the mutant comprises the mutations selected from the group consisting of: (1) G230A, S470A and S477A; (2) S160C, V170C, G230A and A463L; (3) S160C, V170C, S470A and S477A; (4) S160C, V170C, G230A, S470A and S477A; (5) S160C, V170C, G230A, A463L, S470A and S477A (6) S160C, V170C, E209C, L234C, A463L and S470L; (7) S160C, V170C, E209C, L234C, A463L and I474F; (8) S160C, V170C, E209C, L234C, A463L, S470L, F110G, F111S; and, (9) S160C, V170C, A463L and S470L, and, (10) E209C and L234C. E29. The mutant according to E1, wherein the mutant comprises the mutations selected from S160C, V170C, A463L and S470L and the F1 polypeptide comprises or consists of amino acid residues 110 to 484. E30. The mutant according to any one of E1 to E29 wherein the mutant further comprises the mutations selected from substitution of the amino acid R106G, T107S, E108A and R109S. E31. The mutant according to any one of E1 to E30, wherein the F1 polypeptide lacks the entire cytoplasmic domain. E32. The mutant according to any one of E1 to E30 wherein the F1 polypeptide lacks the cytoplasmic domain and a portion of the transmembrane domain. E33. The mutant according to any one of E1 to E30 wherein the F1 polypeptide lacks the cytoplasmic domain all the entire transmembrane domain. E34. The mutant according to any one of E1 to E30, wherein the F1 polypeptide lacks the cytoplasmic domain and the transmembrane domain E35. The mutant according to any one of E1 to E33, wherein the F1 polypeptide comprises or consists of amino acid residues 110 to 481. E36. The mutant according to any one of E1 to E33, wherein the F1 polypeptide comprises or consists of amino acid residues 110 to 484. E37. The mutant according to any one of E1 to E30, wherein the F1 polypeptide comprises the ectodomain, the transmembrane domain and the cytoplasmic domain. In a preferred embodiment, the mutant comprises the full length F1 polypeptide and the full length F2 polypeptide. E38. The mutant according to any one of E1 to E37, wherein the mutant is linked to a trimerization domain. E39. The mutant according to E38, wherein the trimerization domain is a GCN4 leucine zipper or a phage T4 fibritin foldon. E40. The mutant according to E39, wherein the trimerization domain is a phage T4 fibritin foldon. E41. The mutant according to E40, wherein the trimerization domain is a phage T4 fibritin foldon of SEQ ID NO.7. E42. The mutant according to any one of E38 to E41, wherein the trimerization domain is linked to the C-terminus of the F1 polypeptide. E43. The mutant according to any one of E38 to E42, wherein the trimerization domain is linked to the C-terminus of the F1 polypeptide via a linker. E44. The mutant according to E43, wherein the trimerization domain is linked to the C-terminus of the F1 polypeptide via a linker selected from the group consisting of GG, GS, GGGS or SAIG. E45. The mutant according to E44, wherein the linker is GGGS. E46. The mutant according to E44, wherein the linker is GG. E47. The mutant according to E44, wherein the linker is GS. E48. The mutant according to any one of E1 to E47, wherein the mutant is in the form of a trimer. E49. The mutant according to any one of E1 to E48, wherein the mutant is in the prefusion conformation. E50. The mutant according to any one of E1 to E48, wherein the mutant is in the prefusion conformation and specifically binds to an antibody specific for the PIV3 F ectodomain in the prefusion, but not postfusion, conformation. E51. The mutant of any one of E1 to E50 wherein the wild-type PIV3 F protein is SEQ ID NO:38. E52. The mutant of any one of E1 to E51 wherein the amino acid positions correspond to the amino acid sequence of a reference of SEQ ID NO:38. E53. A nucleic acid comprising at least one coding sequence encoding at least one mutant of a wild-type PIV3 F protein according to any one of embodiments E1-E52, preferably E37, or an immunogenic fragment or immunogenic variant thereof, wherein the nucleic acid comprises at least one heterologous untranslated region (UTR). E54. A nucleic acid according to E53, wherein the at least one heterologous untranslated region is selected from at least one heterologous 5’-UTR and/or at least one heterologous 3’- UTR. E55. A nucleic acid according to any one of the preceding embodiments, wherein the at least one heterologous 3’-UTR comprises or consists of a nucleic acid sequence having at least, at most, exactly, or between any two of 99%, 98%, 97%, 96%, 95%, 90%, 85%, or 80% identity to CΨCGAGCΨGGΨ ACΨGCAΨGCA CGCAAΨGCΨA GCΨGCCCCΨΨ ΨCCCGΨCCΨG GGΨACCCCGA GΨCΨCCCCCG ACCΨCGGGΨC CCAGGΨAΨGC ΨCCCACCΨCC ACCΨGCCCCA CΨCACCACCΨ CΨGCΨAGΨΨC CAGACACCΨC CCAAGCACGC AGCAAΨGCAG CΨCAAAACGC ΨΨAGCCΨAGC CACACCCCCA CGGGAAACAG CAGΨGAΨΨAA CCΨΨΨAGCAA ΨAAACGAAAG ΨΨΨAACΨAAG CΨAΨACΨAAC CCCAGGGΨΨG GΨCAAΨΨΨCG ΨGCCAGCCAC ACCCΨGGAGC ΨAGC. E56. A nucleic acid according to any one of the preceding embodiments, wherein the at least one heterologous 5’-UTR comprises or consists of a nucleic acid sequence having at least, at most, exactly, or between any two of 99%, 98%, 97%, 96%, 95%, 90%, 85%, or 80% identity to GAAΨAAAC ΨAGΨAΨΨCΨΨ CΨGGΨCCCCA CAGACΨCAGA GAGAACCCGC CACC. E57. A nucleic acid according to any one of the preceding embodiments, wherein the nucleic acid comprises at least one poly(A) sequence, preferably comprising 30 to 200 adenosine nucleotides and/or at least one poly(C) sequence, preferably comprising 10 to 40 cytosine nucleotides. E58. A nucleic acid according to any one of the preceding embodiments, wherein the nucleic acid is a DNA or an RNA. E59. A nucleic acid according to any one of the preceding embodiments, wherein the nucleic acid is a coding RNA. E60. A nucleic acid according to E59, wherein the coding RNA is an mRNA, a self-replicating RNA, a circular RNA, or a replicon RNA. E61. A nucleic acid according to any one of the preceding embodiments, wherein the nucleic acid, preferably the coding RNA is an mRNA. E62. A nucleic acid according to E1, wherein the mRNA is not a replicon RNA or a self- replicating RNA. E63. A nucleic acid according to any one of the preceding embodiments E59- E62, wherein the mRNA comprises at least one poly(A) sequence comprising 30 to 200 adenosine nucleotides and the 3’ terminal nucleotide is an adenosine. E64. A nucleic acid according to any one of the preceding embodiments E58 – E63, wherein the RNA, preferably the coding RNA, comprises a 5’-cap structure, preferably m7G, capO, cap1 , cap2, a modified capO or a modified cap1 structure, preferably a 5’- cap1 structure. E65. A nucleic acid according to any one of the preceding embodiments E58– E64, wherein the RNA is codon-optimized. E66. A nucleic acid according to any one of the preceding embodiments E58– E65, wherein the RNA comprises a chemically modified nucleotide. E67. A nucleic acid according to any one of the preceding embodiments E58– E66, wherein the RNA comprises N1-methylpseudouridine substitution. Preferably, all the uridines of the RNA are replaced by N1-methylpseudouridine. E68. A nucleic acid according to any one of the preceding embodiments E58–E67, wherein the RNA is a purified RNA., preferably an RNA that has been purified by RP-HPLC and/or TFF. E69. A nucleic according to any one of the preceding embodiments E58 to E68 wherein the RNA is an RNA,purified by RP-HPLC and/or TFF. E70. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E53 – E69. E71. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E53–E69, wherein the composition comprises at least one pharmaceutically acceptable carrier. E72. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E53–E69, wherein the composition is a multivalent composition comprising a plurality or at least more than one of the nucleic acid according to E53-E69. E73. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E53–E69, wherein the composition comprises RNA with an RNA integrity of 70% or more. E74. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E53–E69, wherein the composition comprises RNA with a capping degree of 70% or more, preferably wherein at least 70%, 80%, or 90% of the mRNA species comprise a Cap1 structure. E75. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E53–E69, wherein the at least one nucleic acid is complexed or associated with or at least partially complexed or partially associated with one or more cationic or polycationic compound, preferably cationic or polycationic polymer, cationic or polycationic polysaccharide, cationic or polycationic lipid, cationic or polycationic protein, cationic or polycationic peptide, or any combinations thereof. E76. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E53–E69, wherein the at least one nucleic acid is complexed or associated with one or more lipids or lipid-based carriers, thereby forming liposomes, lipid nanoparticles (LNP), lipoplexes, and/or nanoliposomes, preferably encapsulating the at least one nucleic acid. E77. A composition comprising at least one nucleic acid according to any one of the preceding embodiments E53–E69, wherein the at least one nucleic acid is complexed with one or more lipids thereby forming lipid nanoparticles. E78. A composition according to any one of the preceding embodiments E76–E77 , wherein the LNP comprises a cationic lipid according to formula III-3: E79. A composition according to any one of the preceding embodiments E76-E78, wherein the LNP comprises a PEG lipid of formula (IVa): E80. A composition according to embodiment E79, wherein n has a mean value ranging from 30 to 60, preferably wherein n has a mean value of about 45, 46, 47, 48, 49, 50, 51 , 52, 53, 54, most preferably wherein n has a mean value of 49 or 45. E81. A composition according to any one of the preceding embodiments E76-E80, wherein the LNP comprises a PEG lipid of formula (IVa): wherein n is an integer selected such that the average molecular weight of the PEG lipid is about 2500g/mol. E82. A composition according to any one of the preceding embodiments E76-E81, wherein the LNP comprises one or more neutral lipids and/or one or more steroid or steroid analogues. E83. A composition according to any one of the preceding embodiments E76-E82, wherein the neutral lipid is 1 ,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), preferably wherein the molar ratio of the cationic lipid to DSPC is in the range from about 2:1 to about 8:1. E84. A composition according to any one of the preceding embodiments E76-E83, wherein the steroid is cholesterol, preferably wherein the molar ratio of the cationic lipid to cholesterol is in the range from about 2:1 to about 1:1. E85. A composition according to any one of the preceding embodiments E76-E84, wherein the LNP comprises (i) at least one cationic lipid, preferably a lipid of formula (III), more preferably lipid Ill-3; (ii) at least one neutral lipid, preferably 1 ,2-distearoyl-sn-glycero-3- phosphocholine (DSPC); (iii) at least one steroid or steroid analogue, preferably cholesterol; and (iv) at least one polymer conjugated lipid, preferably a PEG-lipid derived from formula (IVa, with n = 49), wherein (i) to (iv) are in a molar ratio of about 20-60% cationic lipid, 5-25% neutral lipid, 25-55% sterol, and 0.5-15% PEG-lipid. E86. A composition according to any one of the preceding embodiments E76-E85, wherein the LNP comprises (i) at least one cationic lipid, preferably a lipid of formula (III), more preferably lipid Ill-3; (ii) at least one neutral lipid, preferably 1 ,2-distearoyl-sn-glycero-3- phosphocholine (DSPC); (iii) at least one steroid or steroid analogue, preferably cholesterol; and (iv) at least one polymer conjugated lipid, preferably a PEG-lipid derived from formula (IVa, with n = 45), wherein (i) to (iv) are in a molar ratio of about 20-60% cationic lipid, 5-25% neutral lipid, 25-55% sterol, and 0.5-15% PEG-lipid. E87. A composition according to any one of the preceding embodiments E76-E86, wherein (i) to (iv) are in a molar ratio of about 50:10:38.5:1.5, preferably 47.5:10:40.8:1.7 or more preferably 47.4:10:40.9:1.7. E88. A composition according to any one of the preceding embodiments E76-E87, wherein the nucleic acid is RNA and the composition comprises less than about 20% free (non complexed or non-encapsulated) RNA, preferably less than about 15% free RNA, more preferably less than about 10% free RNA. E89. A composition according to any one of the preceding embodiments E76-E88, wherein the wt/wt ratio of lipid to nucleic acid is from about 10:1 to about 60:1 , preferably from about 20:1 to about 30:1 , for example about 25:1. E90. A composition according to any one of the preceding embodiments E76-E89, wherein the n/p ratio of the LNPs encapsulating the nucleic acid is in a range from about 1 to about 10, preferably in a range from about 5 to about 7, more preferably about 6. E91. A composition according to any one of the preceding embodiments E76-E90, wherein the composition has a polydispersity index (PDI) value of less than about 0.4, preferably of less than about 0.3, more preferably of less than about 0.2, most preferably of less than about 0.1. E92. A composition compris according to any one of the preceding embodiments E76-E91, wherein the LNPs have a Z-average size in a range of about 60nm to about 120nm, preferably less than about 120nm, more preferably less than about 100nm, most preferably less than about 80nm. E93. A composition according to any one of the preceding embodiments E76-E92, wherein the LNPs comprise less than about 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1% LNPs that have a particle size exceeding about 500nm. E94. A composition according to any one of the preceding embodiments E76-E93, wherein the LNPs comprise less than about 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1% LNPs that have a particle size smaller than about 20nm. E95. A composition according to any one of the preceding embodiments E76-E94, wherein the LNP comprises (i) at least one cationic lipid; (ii) at least one neutral lipid; (iii) at least one steroid or steroid analogue; and (iv) at least one PEG-lipid, wherein (i) to (iv) are in a molar ratio of about 20-60% cationic lipid, 5-25% neutral lipid, 25-55% sterol, and 0.5-15% PEG-lipid. E96. A composition according to any one of the preceding embodiments E76-E95, wherein the LNP comprises (i) at least one cationic lipid according to formula III-3; (ii) DSPC; (iii) cholesterol; and (iv) a PEG-lipid, according to formula IVa, wherein (i) to (iv) are in a molar ratio of about 20-60% cationic lipid, 5-25% neutral lipid, 25-55% sterol, and 0.5-15% PEG-lipid. E97. A composition according to any one of the preceding embodiments E70-E97, wherein the composition is a lyophilized composition. 3. EXAMPLES OF RSV F PROTEIN MUTANT OR NUCLEIC ACID ENCODING A RSV F PROTEIN MUTANT THAT CAN BE INCLUDED IN THE IMMUNOGENIC COMPOSITION OF THE PRESENT INVENTION. In some embodiments, the immunogenic composition of the present invention comprises a RSV F protein mutant or a nucleic acid encoding a RSV F protein mutant. In some embodiments, the immunogenic composition of the present invention comprises a RSV F protein mutant or a nucleic acid encoding a RSV F protein mutant disclosed in the following embodiments. In some embodiments, the immunogenic composition further comprises an RSV antigen selected from the group consisting of a mutant of a wild-type RSV F protein of subtype A and a nucleic acid, preferably modRNA encoding a mutant of a wild-type RSV F protein of subtype A. Preferably, the mutant is in the form of a trimer. Preferably, the mutant is in the prefusion conformation. Preferably, the mutant is in the prefusion conformation and is in the form of a trimer. Preferably, the RSV antigen is disclosed in one of WO2009/079796, WO2010/149745, WO2011/008974, WO2014/160463, WO2014/174018, WO2014/202570, WO2015/013551, WO2015/177312, WO2017/005848, WO2017/174564, WO2017/005844, WO2017/109629, WO2022/002894 and WO2018/109220. In some embodiment, the RSV antigen is a mutant of a wild-type RSV F protein of subtype A or a nucleic acid, preferably modRNA, encoding a mutant of a wild-type RSV F protein of subtype A comprising the mutations T103C, I148C, S190I, and D486S. In some embodiments, the composition further comprises an RSV antigen selected from the group consisting of a mutant of a wild-type RSV F protein of subtype B and a nucleic acid, preferably modRNA encoding a mutant of a wild-type RSV F protein of subtype B. Preferably, the mutant is in the form of a trimer. Preferably, the mutant is in the prefusion conformation. Preferably, the mutant is in the prefusion conformation and is in the form of a trimer. Preferably, the RSV antigen is disclosed in one of WO2009/079796, WO2010/149745, WO2011/008974, WO2014/160463, WO2014/174018, WO2014/202570, WO2015/013551, WO2015/177312, WO2017/005848, WO2017/174564, WO2017/005844, WO2017/109629, WO2022/002894 and WO2018/109220. In some embodiment, the RSV antigen is a mutant of a wild-type RSV F protein of subtype B or a nucleic acid, preferably modRNA, encoding a mutant of a wild-type RSV F protein of subtype B comprising the mutations T103C, I148C, S190I, and D486S. In some embodiments, the composition further comprises an RSV A antigen selected from the group consisting of a mutant of a wild-type RSV F protein of subtype A and a nucleic acid, preferably modRNA encoding a mutant of a wild-type RSV F protein of subtype A and an RSV B antigen selected from the group consisting of a mutant of a wild-type RSV F protein of subtype B and a nucleic acid, preferably modRNA encoding a mutant of a wild-type RSV F protein of subtype B. Preferably, the mutants are in the form of a trimer. Preferably, the mutants are in the prefusion conformation. Preferably, the mutants are in the prefusion conformation and is in the form of a trimer. Preferably, the RSV A and B antigens are disclosed in one of WO2009/079796, WO2010/149745, WO2011/008974, WO2014/160463, WO2014/174018, WO2014/202570, WO2015/013551, WO2015/177312, WO2017/005848, WO2017/174564, WO2017/005844, WO2017/109629, WO2022/002894 and WO2018/109220. In some embodiment, the RSV A antigen is a mutant of a wild-type RSV F protein of subtype A or a nucleic acid, preferably modRNA, encoding a mutant of a wild-type RSV F protein of subtype A comprising the mutations T103C, I148C, S190I, and D486S and the RSV B antigen is a mutant of a wild-type RSV F protein of subtype B or a nucleic acid, preferably modRNA, encoding a mutant of a wild-type RSV F protein of subtype B comprising the mutations T103C, I148C, S190I, and D486S. In some embodiments, the immunogenic composition further comprises a pharmaceutically acceptable carrier. In some embodiments, the immunogenic composition is a vaccine. In addition to the immunogenic component, the vaccine may further comprise an immunomodulatory agent, such as an adjuvant. Examples of suitable adjuvants include aluminum salts such as aluminum hydroxide and/or aluminum phosphate; oil-emulsion compositions (or oil-in-water compositions), including squalene-water emulsions, such as MF59 (see e.g., WO 90/14837); saponin formulations, such as, for example, QS21 and Immunostimulating Complexes (ISCOMS) (see e.g., U.S. Pat. No.5,057,540; WO 90/03184, WO 96/11711, WO 2004/004762, WO 2005/002620); bacterial or microbial derivatives, examples of which are monophosphoryl lipid A (MPL), 3-O-deacylated MPL (3dMPL), CpG- motif containing oligonucleotides, ADP-ribosylating bacterial toxins or mutants thereof, such as E. coli heat labile enterotoxin LT, cholera toxin CT, and the like. It is also possible to use vector-encoded adjuvant, e.g., by using heterologous nucleic acid that encodes a fusion of the oligomerization domain of C4-binding protein (C4 bp) to the antigen of interest (e.g., Solabomi et al., 2008, Infect Immun 76: 3817-23). In certain embodiments the compositions hereof comprise aluminum as an adjuvant, e.g., in the form of aluminum hydroxide, aluminum phosphate, aluminum potassium phosphate, or combinations thereof, in concentrations of 0.05-5 mg, e.g., from 0.075-1.0 mg, of aluminum content per dose. In some embodiments, the immunogenic composition described herein further comprises a liposomal adjuvant. Contemplated herein is the use of any liposomal adjuvant. In one embodiment, the liposomal adjuvant is AS01. AS01 comprises 3-O-deacylated monophosphoryl lipid A (3D-MPL) and QS21 in a “quenched form” with cholesterol (See U.S. Patent No.10,039,823). In AS01, the lipid bilayer is comprised of a neutral lipid that is “non- crystalline” at room temperature, such as dioleoyl phosphatidylcholine, cholesterol, MPLA, and QS-21 (See U.S. Patent No.10,039,823 and WO 1996/033739). During manufacture of AS01, small unilamellar liposomal vesicles (SUV) are first created and purified QS-21 is then added to the SUV. The QS-21 imparts unique properties in that it binds to the liposomal cholesterol where it causes perforations (holes) or other permanent structural changes in the liposomes (See, e.g., Paepenmuller et al., 2014, Int. J. Pharm., 475: 138-46). A reduced amount of free QS-21 presumably resulted in reduced local injection pain often caused by free QS-21 (See, e.g., Waite et al., 2001, Vaccine, 19: 3957-67; Mbawuike et al., 2007, Vaccine, 25: 3263-69). In some embodiments, AS01 contains cholesterol (sterol) at a mole percent concentration of between about 1 and about 50% (mol/mol), preferably between about 20 and about 25% (mol/mol) (See U.S. Patent No.10,039,823). In some embodiments, AS01 (including for example, AS01A, AS01B, AS01C, AS01D, AS01E, and AS015) comprises dioleoyl phosphatidylcholine (DOPC), cholesterol, MPLA, for example 3D- MPL, and QS-21. In further embodiments, the liposomal adjuvant is selected from the group consisting of AS01A, AS01B, AS01C, AS01D, AS01E, and AS015. In one embodiment, the liposomal adjuvant is AS01A. In some embodiments, AS01A comprises 3D-MPL, toll-like receptor 4 agonist, and QS-21. In one embodiment, the liposomal adjuvant is AS01B. In some embodiments, AS01B comprises 1000 μg per dose DOPC, 250 μg per dose cholesterol, 50 μg per dose 3D-MPL, 50 μg per dose QS21, phosphate NaCl buffer, and water to a volume of 0.5 ml (See U.S. Patent No.10,039,823). In one embodiment, the liposomal adjuvant is AS01E. In some embodiments, AS01E comprises the same components as AS01B but at a lower concentration. In some embodiments, AS01E comprises 500 μg per dose dioleoyl phosphatidylcholine (DOPC), 125 μg per dose cholesterol, 25 μg per dose 3D-MPL, 25 μg per dose QS21, phosphate NaCl buffer, and water to a volume of 0.5 ml (See U.S. Patent No.10,039,823). In one embodiment, the liposomal adjuvant is AS015. In some embodiments, AS015 comprises dioleoyl phosphatidylcholine (DOPC), cholesterol, 3D-MPL, QS-21, and CpG. In some embodiments, the immunogenic composition described herein further comprises a liposomal adjuvant, wherein the liposomal adjuvant is LiNA-1. In some embodiments, LiNA-1 comprises MPLA and a saponin. In some embodiments, LiNA-1 comprises MPLA and QS-21. In other embodiments, LiNA-1 comprises phosphorylated hexaAcyl disaccharide (PHAD^®) (i.e., monophosphoryl lipid A (synthetic) available from Avanti^® polar lipids) and QS-21. In another particular embodiment, LiNA-1 comprises PHAD^®, QS-21, cholesterol, and DOPC. In another particular embodiment, LiNA-1 comprises 3D- PHAD^®, QS-21, cholesterol, and DOPC. In another particular embodiment, LiNA-1 comprises the following components per 0.5 mL dose: (i) 50 µg MPLA (i.e., 3D-PHAD^®), (ii) 250 µg cholesterol, (iii) 50 µg QS-21, and (iv) 1000 µg DOPC. In another particular embodiment, LiNA- 1 comprises the following components per 0.5 mL dose: (i) 50 µg MPLA (i.e., PHAD^®), (ii) 250 µg cholesterol, (iii) 50 µg QS-21, and (iv) 1000 µg DOPC. In some embodiments, the immunogenic composition described herein further comprises a liposomal adjuvant, wherein the liposomal adjuvant is ALFQ. In some embodiments, ALFQ comprises MPLA and saponin (See US Patent No.10,434,167). In some embodiments, ALFQ comprises a lipid bilayer comprising phospholipids in which the hydrocarbon chains have a melting temperature in water of ≥ 23° C. In further embodiments, ALFQ comprises cholesterol at a mole percent concentration of greater than about 50% (mol/mol). In certain embodiments, ALFQ comprises between about 55% and about 71% (mol/mol) cholesterol. In particular embodiments, ALFQ comprises about 55% (mol/mol) cholesterol. In some embodiments, ALFQ comprises MPLA and QS-21. In other embodiments, ALFQ comprises monophosphoryl 3-deacyl lipid A phosphorylated hexaacyl disaccharide (3D-PHAD^®) (i.e., monophosphoryl 3-Deacyl Lipid A (synthetic) available from Avanti^® polar lipids) and a saponin. In another particular embodiment, ALFQ comprises 3D- PHAD^®, QS-21, dimyristoyl phosphatidylcholine (DMPC), dimyristoyl phosphatidylglycerol (DMPG), and cholesterol. In another particular embodiment, ALFQ comprises (i) 7.0 ± 3.5 mg/mL DMPC, (ii) 0.78 ± 0.39 mg/ml DMPG, (iii) 5.4 ± 2.7 mg/ml cholesterol, (iv) 0.2 ± 0.1 mg/mL MPLA (3D-PHAD^®), and (v) 0.1 ± 0.05 mg/ml QS-21. In some embodiments, the immunogenic composition described herein further comprises a liposomal adjuvant, wherein the liposomal adjuvant is LiNA-2. In some embodiments, LiNA-2 comprises MPLA and saponin. In some embodiments, LiNA-2 comprises a lipid bilayer comprising phospholipids in which the hydrocarbon chains have a melting temperature in water of ≥ 23° C. In further embodiments, LiNA-2 comprises cholesterol at a mole percent concentration of greater than about 50% (mol/mol). In certain embodiments, LiNA-2 comprises between about 55% to about 71% (mol/mol) cholesterol. In particular embodiments, LiNA-2 comprises about 55% (mol/mol) cholesterol. In some embodiments, LiNA-2 comprises MPLA and QS-21. In other embodiments, LiNA-2 comprises monophosphoryl 3-deacyl lipid A phosphorylated hexaacyl disaccharide (3D- PHAD^®) and a saponin. In another particular embodiment, LiNA-2 comprises 3D-PHAD^®, QS-21, dimyristoyl phosphatidylcholine (DMPC), dimyristoyl phosphatidylglycerol (DMPG) and cholesterol. In another particular embodiment, LiNA-2 comprises (i) 14 ± 7 mg/mL DMPC, (ii) 1.6 ± 0.8 mg/ml DMPG, (iii) 11 ± 6 mg/ml cholesterol, (iv) 0.40 ± 0.20 mg/mL MPLA (3D-PHAD^®), and (v) 0.20 ± 0.10 mg/ml QS-21. In yet another particular embodiment, LiNA-2 comprises (i) 28 ± 14 mg/mL DMPC, (ii) 3.2 ± 1.6 mg/ml DMPG, (iii) 22 ± 11 mg/ml cholesterol, (iv) 0.80 ± 0.40 mg/mL MPLA (3D-PHAD^®), and (v) 0.40 ± 0.20 mg/ml QS-21. In some embodiments, the immunogenic composition described herein further comprises an adjuvant, wherein the adjuvant is a nucleotide adjuvant. In some embodiments, the nucleotide adjuvant comprises DNA. In some embodiments, the nucleotide adjuvant comprises DNA that is single-stranded. In some embodiments, the nucleotide adjuvant comprises DNA that is double-stranded. In some embodiments, the immunogenic composition described herein further comprises an adjuvant, wherein the adjuvant is a CpG oligonucleotide. A CpG oligonucleotide is a short nucleic acid molecule containing a cytosine followed by a guanine linked by a phosphate bond in which the pyrimidine ring of the cytosine is unmethylated. A CpG motif is a pattern of bases that include an unmethylated central CpG surrounded by at least one base flanking (on the 3' and the 5' side of) the central CpG. CpG oligonucleotides include both D and K oligonucleotides. The entire CpG oligonucleotide may be unmethylated or portions may be unmethylated. Examples of CpG oligonucleotides useful in the methods provided by the present disclosure include those disclosed in U.S. Patent Nos.6194388, 6207646, 6214806, 628371, 6239116, and 6339068. In some embodiments, the immunogenic composition described herein further comprises an adjuvant, wherein the adjuvant comprises oligodeoxynucleotides (ODN). As used herein, “CpG ODN” refers to cytosine-phosphoguanosine (CpG) motif-containing oligodeoxynucleotide. In some embodiments, the immunogenic composition described herein further comprises an adjuvant, wherein the adjuvant comprises CpG ODN. In some embodiments, the CpG ODN is a toll-like receptor 9 (TLR9) agonist. In some embodiments, the CpG ODN adjuvant contains palindromic repeats. In some embodiments, the CpG oligonucleotide adjuvant contains palindromic repeats following the formula 5’-purine-purine-CG-pyrimidine-pyrimidine-3’. Different classes of CpG immunostimulatory oligonucleotides have been identified and are described in greater detail in WO 2010/125480. The immunogenic compositions described herein can comprise adjuvants comprising these different classes of CpG immunostimulatory oligonucleotides. The immunogenic compositions described can comprise adjuvants comprising oligonucleotides that are A-Class, B-Class, C-Class, T-Class, P-Class or any Class with an E modification. In some embodiments, the immunogenic composition described herein further comprises a CPG ODN adjuvant, wherein the CpG ODN adjuvant comprises or consists of the following nucleic acid sequence: 5’ TCGTCGTTTTTCGGTGCTTTT 3’ (SEQ ID NO: SEQ ID NO:41; CpG 24555). In some embodiments, the immunogenic composition described herein further comprises a CPG ODN adjuvant, wherein the CpG ODN adjuvant comprises or consists of the following nucleic acid sequence: 5’ TGACTGTGAACGTTCGAGATGA 3’ (SEQ ID NO: 42; CpG 1018). In some embodiments, the immunogenic composition described herein further comprises a CPG ODN adjuvant, wherein the CpG ODN adjuvant comprises or consists of the following nucleic acid sequence: 5’ T*C*G*T*C*G*T*T*T*T*T*C*G*G*T*G*C*T*T*T*T 3’ (SEQ ID NO:43), wherein * indicates a phosphorothioate linkage. SEQ ID NO:43 corresponds to the sequence of CpG 24555 wherein each of the internucleotide linkages are phosphorothioate linkages. CpG 24555 is a TLR9 agonist with potent Th1 cell activity that stimulates strong B-cell and NK-cell activation and is described in U.S. Patent No.8,552,165, incorporated by reference herein. As used herein, “CpG 24555” refers to a sequence comprising or consisting of the sequence of either SEQ ID NO:41 or SEQ ID NO:43. In some embodiments, at least one CG dinucleotide within CpG 24555 comprises a cytosine that is unmethylated. In some embodiments, at least two or three CG dinucleotides within CpG 24555 comprise a cytosine that is unmethylated. In a particular embodiment, each CG dinculeotide within CpG 24555 comprises a cytosine that is unmethylated. In some embodiments, the immunogenic composition described herein further comprises an adjuvant, wherein the adjuvant is a Toll-like receptor 7 (TLR7), Toll-like receptor 8 (TLR8), or Toll-like receptor 7/8 (TLR7/8) modulating compound. In some embodiments, the immunogenic composition described herein further comprises an adjuvant, wherein the adjuvant is a TLR7, TLR8, or TLR7/8 modulating compound conjugated to a lipophilic moiety (i.e., cholesterol or tocopherol) to form an amphiphilic molecule. D. USES OF THE HMPV F PROTEIN MUTANTS, NUCLEIC ACID, AND COMPOSITIONS The present disclosure also relates to use of a hMPV F protein mutant disclosed herein, nucleic acids encoding a hMPV F protein mutant disclosed herein, or vectors for expressing a hMPV F protein mutant disclosed herein, or compositions comprising a hMPV F protein mutant or nucleic acids disclosed herein. In several embodiments, the present disclosure provides a method of eliciting an immune response to hMPV A and/or hMPV B in a subject, comprising administering to the subject an effective amount of a hMPV F protein mutant disclosed herein, a nucleic acid encoding a hMPV F protein mutant disclosed herein, or a composition comprising a hMPV F protein mutant or nucleic acid disclosed herein. In some particular embodiments, the present disclosure provides a method of preventing hMPV A and/or hMPV B infection in a subject, comprising administering to the subject an effective amount of a pharmaceutical composition, such as a vaccine, comprising a hMPV F protein mutant disclosed herein, a nucleic acid encoding a hMPV F protein mutant disclosed herein, or a vector expressing a hMPV F protein mutant disclosed herein. In some embodiments, the subject is a human. In some particular embodiments, the human is a child, such as an infant. In some other particular embodiments, the human is a woman, particularly a pregnant woman. In some other particular embodiments, the human is a an adult greater than 50 years of age. In several embodiments, the present disclosure provides an hMPV F protein mutant disclosed herein, a nucleic acid encoding a hMPV F protein mutant disclosed herein, or a composition comprising a hMPV F protein mutant or nucleic acid disclosed herein for use as a vaccine. In several embodiments, the present disclosure provides the use of hMPV F protein mutant disclosed herein, a nucleic acid encoding a hMPV F protein mutant disclosed herein, or a composition comprising a hMPV F protein mutant or nucleic acid disclosed herein for the manufacture of a medicament, preferably a vaccine. In several embodiments, the present disclosure provides an hMPV F protein mutant disclosed herein, a nucleic acid encoding hMPV F protein mutant disclosed herein, or a composition comprising a hMPV F protein mutant or nucleic acid disclosed herein for use in a method of eliciting an immune response to hMPV A and/or hMPV B in a subject, said method comprising administering to the subject an effective amount of said protein mutant, nucleic acid or composition. In several embodiments, the present disclosure provides an hMPV F protein mutant disclosed herein, a nucleic acid encoding a hMPV F protein mutant disclosed herein, or a composition comprising hMPV F protein mutant or nucleic acid disclosed herein for use in preventing hMPV A and/or hMPV B infection in a subject, said method comprising administering to the subject an effective amount of said protein mutant, nucleic acid or composition. In some embodiments, the subject is a human. In some particular embodiments, the human is a child, such as an infant. In some other particular embodiments, the human is a woman, particularly a pregnant woman. The composition may be administered to the subject with or without administration of an adjuvant. The effective amount administered to the subject is an amount that is sufficient to elicit an immune response against an hMPV A and/or hMPV B, such as hMPV A and/or hMPV B F protein, in the subject. Subjects that can be selected for treatment include those that are at risk for developing an hMPV A and/or hMPV B infection because of exposure or the possibility of exposure to hMPV A and/or hMPV B. Because nearly all humans are infected with hMPV A and/or hMPV B by the age of 5, the entire birth cohort is included as a relevant population for immunization. This could be done, for example, by beginning an immunization regimen anytime from birth to 6 months of age, from 6 months of age to 5 years of age, in pregnant women (or women of child-bearing age) to protect their infants by passive transfer of antibody, family members of newborn infants or those still in utero, and subjects greater than 50 years of age. Subjects at greatest risk of hMPV A and/or hMPV B infection with severe symptoms (e.g. requiring hospitalization) include children with prematurity, bronchopulmonary dysplasia, and congenital heart disease. Administration of the compositions provided by the present disclosure, such as pharmaceutical compositions, can be carried out using standard routes of administration. Non- limiting embodiments include parenteral administration, such as intradermal, intramuscular, subcutaneous, transcutaneous, mucosal, or oral administration. The total dose of the composition provided to a subject during one administration can be varied as is known to the skilled practitioner. It is also possible to provide one or more booster administrations of one or more of the vaccine compositions. If a boosting vaccination is performed, typically, such a boosting vaccination will be administered to the same subject at a moment between one week and 10 years, preferably between two weeks and six months, after administering the composition to the subject for the first time (which is in such cases referred to as “priming vaccination”). In alternative boosting regimens, it is also possible to administer different vectors, e.g., one or more adenovirus, or other vectors such as modified vaccinia virus of Ankara (MVA), or DNA, or protein, to the subject after the priming vaccination. It is, for instance, possible to administer to the subject a recombinant viral vector hereof as a prime, and boosting with a composition comprising hMPV F protein mutant as disclosed herein. In certain embodiments, the administration comprises a priming administration and at least one booster administration. In certain other embodiments, the administration is provided annually. In still other embodiments, the administration is provided annually together with an influenza vaccine. The vaccines provided by the present disclosure may be used together with one or more other vaccines. For example, in adults they may be used together with an influenza vaccine, Prevnar, tetanus vaccine, diphtheria vaccine, RSV vaccine such as Abryvso^TM or Arexvy^TM, COVID19 vaccine and pertussis vaccine. For pediatric use, vaccines provided by the present disclosure may be used with any other vaccine indicated for pediatric patients. E. RNA MOLECULE In some aspects of the present disclosure, an RNA is or comprises messenger RNA (mRNA) that relates to an RNA transcript which encodes a polypeptide. In some aspects, an RNA disclosed herein comprises: a 5′ cap disclosed herein; a 5′ untranslated region comprising a cap proximal sequence (5′ UTR), a sequence encoding a payload (e.g., a hMPV F protein mutant); a 3′ untranslated region (3′ UTR); and a polyadenylate (Poly A) sequence. In some aspects, an RNA disclosed herein comprises the following components in 5′ to 3′ orientation: a 5′ cap comprising a 5′ cap disclosed herein; a 5′ untranslated region comprising a cap proximal sequence (5′ UTR), a sequence encoding a payload (e.g., a hMPV F protein mutant); a 3′ untranslated region (3′ UTR); and a Poly-A sequence. 1. MODIFIED NUCLEOBASES In the present disclosure the RNA molecules may comprise modified nucleobases which may be incorporated into modified nucleosides and nucleotides. In some aspects, the RNA molecule may include one or more modified nucleotides. Naturally occurring nucleotide modifications are known in the art. In some aspects, the RNA molecule may include a modified nucleotide. Non-limiting examples of modified nucleotides that may be included in the RNA molecule include pseudouridine, N1-methylpseudouridine, 5-methyluridine, 3-methyl-uridine, 5-methoxy-uridine, 5-aza-uridine, 6-aza-uridine, 2-thio-5-aza-uridine, 2-thio-uridine, 4-thio-uridine, 4-thio- pseudouridine, 2-thio-pseudouridine, 5-hydroxy-uridine, 5-aminoallyl-uridine, 5-halo-uridine (e.g., 5-iodo-uridine or 5-bromo-uridine), uridine 5-oxyacetic acid, uridine 5-oxyacetic acid methyl ester, 5-carboxymethyl-uridine, 1-carboxymethyl-pseudouridine, 5-carboxy hydroxymethyl-uridine, 5-carboxy hydroxy methyl-uridine methyl ester, 5- methoxycarbonylmethyl-uridine, 5-methoxycarbonylmethyl-2-thio-uridine, 5-aminomethyl-2- thio-uridine, 5-methylaminomethyl-uridine, 1-ethyl-pseudouridine, 5-methylaminomethyl-2- thio-uridine, 5-methylaminomethyl-2-seleno-uridine, 5-carbamoylmethyl-uridine, 5- carboxymethylaminomethyl-uridine, 5-carboxymethylaminomethyl-2-thio-uridine, 5-propynyl- uridine, 1-propynyl-pseudouridine, 5-taurinomethyl-uridine, 1-taurinomethyl-pseudouridine, 5- taurinomethyl-2-thio-uridine, 1-taurinomethyl-4-thio-pseudouridine, 5-methyl-2-thio-uridine, 1- methyl-4-thio-pseudouridine, 4-thio-1-methyl-pseudouridine, 3-methyl-1-pseudouridine, 2- thio-1-methyl-pseudouridine, 1-methyl-1-deaza-pseudouridine, 2-thio-1-methyl-1-deaza- pseudouridine, dihydrouridine, dihydropseudouridine, 5,6-dihydrouridine, 5-methyl- dihydrouridine, 2-thio-dihydrouridine, 2-thio-dihydropseudouridine, 2-methoxy-uridine, 2- methoxy-4-thio-uridine, 4-methoxy-pseudouridine, 4-methoxy-2-thio-pseudouridine, N1- methyl-pseudouridine, 3-(3-amino-3-carboxypropyl)uridine, 1-methyl-3-(3-amino-3- carboxypropyl)pseudouridine, 5-(isopentenylaminomethyl)uridine, 5- (isopentenylaminomethyl)-2-thio-uridine, a-thio-uridine, 2′-O-methyl-uridine, 5,2′-O-dimethyl- uridine, 2′-O-methyl-pseudouridine, 2-thio-2′-O-methyl-uridine, 5-methoxycarbonylmethyl-2′- O-methyl-uridine, 5-carbamoylmethyl-2′-O-methyl-uridine, 5-carboxymethylaminomethyl-2′-O- methyl-uridine, 3,2′-O-dimethyl-uridine, 5-(isopentenylaminomethyl)-2′-O-methyl-uridine, 1- thio-uridine, deoxythymidine, 2′-F-ara-uridine, 2′-F-uridine, 2′-OH-ara-uridine, 5-(2- carbomethoxyvinyl) uridine, 5-[3-(1-E-propenylamino)uridine, any other modified uridine known in the art, or combinations thereof. In some aspects of the present disclosure, modified nucleotides include any one of N1-methylpseudouridine or pseudouridine. In some aspects, the RNA molecule comprises nucleotides that are N1- methylpseudouridine modified. In some aspects, the RNA molecule comprises nucleotides that are a pseudouridine modified. In some aspects, an RNA comprises a modified nucleoside in place of at least one uridine. In some aspects, an RNA comprises a modified nucleoside in place of each uridine. In some aspects, the RNA molecule comprises a sequence having at least one uridine replaced by N1-methylpseudouridine. In some aspects, the RNA molecule comprises a sequence having all uridines replaced by N1-methylpseudouridine. N1-methylpseudouridine is designated in sequences as “Ψ”. The term “uracil,” as used herein, describes one of the nucleobases that may occur in the nucleic acid of RNA. The term “uridine,” as used herein, describes one of the nucleosides that may occur in RNA. “Pseudouridine” is one example of a modified nucleoside that is an isomer of uridine, where the uracil is attached to the pentose ring via a carbon-carbon bond instead of a nitrogen-carbon glycosidic bond. In some aspects, the RNA molecule comprises a nucleic acid sequence having at least one uridine replaced by pseudouridine. In some aspects, the RNA molecule comprises a nucleic acid sequence having at least, at most, exactly, or between any two of 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% of uridines replaced by pseudouridine. In some aspects, the RNA molecule comprises a nucleic acid sequence having all uridines replaced by pseudouridine. Modifications that may be present in the RNA molecules further include, for example, m5C (5-methylcytidine), m5U (5-methyluridine), m6A (N6-methyladenosine), s2U (2- thiouridine), Um (2′-O-methyluridine), m1A (1-methyladenosine); m2A (2-methyladenosine); Am (2-1-O-methyladenosine); ms2m6A (2-methylthio-N6-methyladenosine); i6A (N6- isopentenyladenosine); ms2i6A (2-methylthio-N6isopentenyladenosine); io6A (N6-(cis- hydroxyisopentenyl)adenosine); ms2io6A (2-methylthio-N6-(cis-hydroxyisopentenyl) adenosine); g6A (N6-glycinylcarbamoyladenosine); t6A (N6-threonyl carbamoyladenosine); ms2t6A (2-methylthio-N6-threonyl carbamoyladenosine); m6t6A (N6-methyl-N6- threonylcarbamoyladenosine); hn6A(N6-hydroxynorvalylcarbamoyl adenosine); ms2hn6A (2- methylthio-N6-hydroxynorvalyl carbamoyladenosine); Ar(p) (2′-O-ribosyladenosine (phosphate)); I (inosine); mil (1-methylinosine); m’lm (1,2′-O-dimethylinosine); m3C (3- methylcytidine); Cm (2T-O-methylcytidine); s2C (2-thiocytidine); ac4C (N4-acetylcytidine); f5C (5-formylcytosine); m5Cm (5,2-O-dimethylcytidine); ac4Cm (N4acetyl2TOmethylcytidine); k2C (lysidine); m1G (1-methylguanosine); m2G (N2-methylguanosine); m7G (7- methylguanosine); Gm (2′-O-methylguanosine); m22G (N2,N2-dimethylguanosine); m2Gm (N2,2′-O-dimethylguanosine); m22Gm (N2,N2,2′-O-trimethylguanosine); Gr(p) (2′-O- ribosylguanosine (phosphate)); yW (wybutosine); o2yW (peroxywybutosine); OHyW (hydroxywybutosine); OHyW* (undermodified hydroxywybutosine); imG (wyosine); mimG (methylguanosine); Q (queuosine); oQ (epoxyqueuosine); galQ (galtactosyl-queuosine); manQ (mannosyl-queuosine); preQo (7-cyano-7-deazaguanosine); preQi (7-aminomethyl-7- deazaguanosine); G* (archaeosine); D (dihydrouridine); m5Um (5,2′-O-dimethyluridine); s4U (4-thiouridine); m5s2U (5-methyl-2-thiouridine); s2Um (2-thio-2′-O-methyluridine); acp3U (3- (3-amino-3-carboxypropyl)uridine); ho5U (5-hydroxyuridine); mo5U (5-methoxyuridine); cmo5U (uridine 5-oxyacetic acid); mcmo5U (uridine 5-oxyacetic acid methyl ester); chm5U (5- (carboxyhydroxymethyl)uridine)); mchm5U (5-(carboxyhydroxymethyl)uridine methyl ester); mcm5U (5-methoxycarbonyl methyluridine); mcm5Um (S-methoxycarbonylmethyl-2-O- methyluridine); mcm5s2U (5-methoxycarbonylmethyl-2-thiouridine); nm5s2U (5-aminomethyl- 2-thiouridine); mnm5U (5-methylaminomethyluridine); mnm5s2U (5-methylaminomethyl-2- thiouridine); mnm5se2U (5-methylaminomethyl-2-selenouridine); ncm5U (5-carbamoylmethyl uridine); ncm5Um (5-carbamoylmethyl-2′-O-methyluridine); cmnm5U (5- carboxymethylaminomethyluridine); cnmm5Um (5-carboxymethy 1 aminomethyl-2-L- Omethyluridine); cmnm5s2U (5-carboxymethylaminomethyl-2-thiouridine); m62A (N6,N6- dimethyladenosine); Tm (2′-O-methylinosine); m4C (N4-methylcytidine); m4Cm (N4,2-O- dimethylcytidine); hm5C (5-hydroxymethylcytidine); m3U (3-methyluridine); cm5U (5- carboxymethyluridine); m6Am (N6,T-O-dimethyladenosine); rn62Am (N6,N6,O-2- trimethyladenosine); m2′7G (N2,7-dimethylguanosine); m2′2′7G (N2,N2,7- trimethylguanosine); m3Um (3,2T-O-dimethyluridine); m5D (5-methyldihydrouridine); f5Cm (5- formyl-2′-O-methylcytidine); m1Gm (1,2′-O-dimethylguanosine); m’Am (1,2-O-dimethyl adenosine) irinomethyluridine); tm5s2U (S-taurinomethyl-2-thiouridine)); imG-14 (4-demethyl guanosine); imG2 (isoguanosine); ac6A (N6-acetyladenosine), hypoxanthine, inosine, 8-oxo- adenine, 7-substituted derivatives thereof, dihydrouracil, pseudouracil, 2-thiouracil, 4- thiouracil, 5-aminouracil, 5-(C1-C6)-alkyluracil, 5-methyluracil, 5-(C2-Ce)-alkenyluracil, 5-(C2- Ce)-alkynyluracil, 5-(hydroxymethyl)uracil, 5-chlorouracil, 5-fluorouracil, 5-bromouracil, 5- hydroxycytosine, 5-(C1-C6)-alkylcytosine, 5-methylcytosine, 5-(C2-C6)-alkenylcytosine, 5- (C2-C6)-alkynylcytosine, 5-chlorocytosine, 5-fluorocytosine, 5-bromocytosine, N2- dimethylguanine, 7-deazaguanine, 8-azaguanine, 7-deaza-7-substituted guanine, 7-deaza-7- (C2-C6)alkynylguanine, 7-deaza-8-substituted guanine, 8-hydroxyguanine, 6-thioguanine, 8- oxoguanine, 2-aminopurine, 2-amino-6-chloropurine, 2,4-diaminopurine, 2,6-diaminopurine, 8-azapurine, substituted 7-deazapurine, 7-deaza-7-substituted purine, 7-deaza-8-substituted purine, hydrogen (abasic residue), m5C, m5U, m6A, s2U, W, or 2′-O-methyl-U. In some aspects, the RNA molecule may include phosphoramidate, phosphorothioate, and/or methylphosphonate linkages. The sequence of the RNA molecule may be modified if desired, for example to increase the efficacy of expression or replication of the RNA, or to provide additional stability or resistance to degradation. For example, the RNA sequence may be modified with respect to its codon usage, for example, to increase translation efficacy and half-life of the RNA. In some aspects, the RNA molecule of the present disclosure comprises an open reading frame having at least one codon modified sequence. A codon modified sequence relates to coding sequences that differ in at least one codon (triplets of nucleotides coding for one amino acid) compared to the corresponding wild type coding sequence. A codon modified sequence may show improved resistance to degradation, improved stability, and/or improved translatability. The sequence of the RNA molecule may be codon optimized or deoptimized for expression in a desired host, such as a human cell. In some aspects, the RNA molecule may include one or more modified nucleotides in addition to any 5’ cap structure. Naturally occurring nucleotide modifications are known in the art. In some aspects, the RNA molecule does not include modified nucleotides, e.g., does not include modified nucleobases, and all of the nucleotides in the RNA molecule are conventional standard ribonucleotides A, U, G and C, with the exception of an optional 5’ cap that may include, for example, 7-methylguanosine, which is further described below. In some aspects, the RNA may include a 5’ cap comprising a 7’-methylguanosine, and the first 1, 2 or 35’ ribonucleotides may be methylated at the 2’ position of the ribose. In some aspects, the RNA molecule described herein is a non-coding RNA molecule. A non-coding RNA (ncRNA) molecule includes a functional RNA molecule that is not translated into a peptide or polypeptide. Non-coding RNA molecules may include highly abundant and functionally important RNA molecules. In some aspects, the non-coding RNA is a functional mRNA molecule that is not translated into a peptide or polypeptide. The non-coding RNA may include modified nucleotides as described herein. Preferably, the RNA molecule is an mRNA The RNA molecules of the present disclosure may be prepared by any method know in the art, including chemical synthesis and in vitro methods, such as RNA in vitro transcription. In some of the aspects, the RNA of the present disclosure is prepared using in vitro transcription. In some aspects, the RNA molecule of the present disclosure is purified, e.g., such as by filtration that may occur via, e.g., ultrafiltration, diafiltration, or, e.g., tangential flow ultrafiltration/diafiltration. In some aspects, the RNA molecule of the present disclosure is lyophilized to be temperature stable. 2. 5′ CAP In some aspects, the RNA molecule described herein includes a 5′ cap which generally “caps” the 5′ end of the RNA and stabilizes the RNA molecule. In some aspects, the 5′ cap moiety is a natural 5′ cap. A “natural 5′ cap” is defined as a cap that includes 7- methylguanosine connected to the 5′ end of an mRNA molecule through a 5′ to 5′ triphosphate linkage. In some aspects, a guanosine nucleoside included in a 5′ cap may be modified, for example, by methylation at one or more positions (e.g., at the 7-position) on a base (guanine), and/or by methylation at one or more positions of a ribose. In some aspects, a guanosine nucleoside included in a 5′ cap comprises a 3′O methylation at a ribose (3′OMeG). In some aspects, a guanosine nucleoside included in a 5′ cap comprises methylation at the 7-position of guanine (m7G). In some aspects, a guanosine nucleoside included in a 5′ cap comprises methylation at the 7-position of guanine and a 3′O methylation at a ribose (m7(3′OMeG)). The 5′ cap may be incorporated during RNA synthesis (e.g., co-transcriptional capping) or may be enzymatically engineered after RNA transcription (e.g., post-transcriptional capping). In some aspects, co-transcriptional capping with a cap disclosed herein improves the capping efficiency of an RNA compared to co-transcriptional capping with an appropriate reference comparator. In some aspects, improving capping efficiency may increase a translation efficiency and/or translation rate of an RNA, and/or increase expression of an encoded polypeptide. In some aspects, capping is performed after purification, e.g., tangential flow filtration, of the RNA molecule. In some aspects, an RNA described herein comprises a 5′ cap or a 5′ cap analog, e.g., a Cap 0, a Cap 1 or a Cap 2. In some aspects, a provided RNA does not have uncapped 5′- triphosphates. In some aspects, the 5′ end of the RNA is capped with a modified ribonucleotide. In some aspects, the 5′ cap moiety is a 5′ cap analog. In some aspects, an RNA may be capped with a 5′ cap analog. Cap structures include, but are not limited to, 7mG(5′)ppp(5′)N,pN2p (Cap 0) and 7mG(5′)ppp(5′)N1mpNp (Cap 1). In some aspects, an RNA described herein comprises a Cap 0. Cap 0 is a N7-methyl guanosine connected to the 5′ nucleotide through a 5′ to 5′ triphosphate linkage, typically referred to as m7G cap or m7Gppp. In the cell, the Cap 0 structure is essential for efficient translation of the mRNA that carries the cap. An additional methylation on the 2′O position of the initiating nucleotide generates Cap 1, or referred to as m7GpppNm, wherein Nm denotes any nucleotide with a 2′O methylation. In some aspects, an RNA described herein comprises a Cap 1, e.g., as described herein. In some aspects, an RNA described herein comprises a Cap 2. In some aspects, a Cap 0 structure comprises a guanosine nucleoside methylated at the 7-position of guanine (m7G). In some aspects, a Cap 0 structure is connected to an RNA via a 5′ to 5′-triphosphate linkage and is also referred to herein as m7Gppp or m7G(5′)ppp(5′).· A 5′ cap may be methylated with the structure m7G (5′) ppp (5′) N (cap-0 structure) or a derivative thereof, wherein N is the terminal 5′ nucleotide of the nucleic acid carrying the 5′ cap, typically the 5′-end of an mRNA. An exemplary enzymatic reaction for capping may include use of Vaccinia Virus Capping Enzyme (VCE) that includes mRNA triphosphatase, guanylyl-transferase and guanine-7-methytransferase, which catalyzes the construction of N7-monomethylated Cap 0 structures. Cap 0 structure plays an important role in maintaining the stability and translational efficacy of the RNA molecule. The 5′ cap of the RNA molecule may be further modified by a 2′-O-Methyltransferase which results in the generation of a Cap 1 structure (m7Gppp [m2′-Ο] N), which may further increase translation efficacy. In some aspects, a Cap 1 structure comprises a guanosine nucleoside methylated at the 7-position of guanine (m7G) and a 2′O methylated first nucleotide in an RNA (2′OmeN₁). In some aspects, a Cap 1 structure is connected to an RNA via a 5′- to 5′-triphosphate linkage and is also referred to herein as m7Gppp(2′OMeN₁) or m7G(5′)ppp(5′)(2′OMeN₁). In some aspects, N₁ is chosen from A, C, G, or U. In some aspects, N₁ is A. In some aspects, N₁ is C. In some aspects, N₁ is G. In some aspects, N₁ is U. In some aspects, a m7G(5′)ppp(5′)(2′OmeN₁) Cap 1 structure comprises a second nucleotide, N₂, which is a cap proximal nucleotide at position 2 and is chosen from A, G, C, or U (m7G(5′)ppp(5′)(2′OmeN₁)N₂). In some aspects, N₂ is A. In some aspects, N₂ is C. In some aspects, N₂ is G. In some aspects, N₂ is U. In some aspects, a Cap 1 structure comprises a guanosine nucleoside methylated at the 7-position of guanine (m7G) and one or more additional modifications, e.g., methylation on a ribose, and a 2′O methylated first nucleotide in an RNA. In some aspects, a Cap 1 structure comprises a guanosine nucleoside methylated at the 7-position of guanine, a 3′O methylation at a ribose (m7(3′OMeG)), and a 2′O methylated first nucleotide in an RNA (2′OMeN₁). In some aspects, a Cap 1 structure is connected to an RNA via a 5′- to 5′- triphosphate linkage and is also referred to herein as m7(3′OMeG)ppp(2′OMeN₁) or m7(3′OMeG)(5′)ppp(5′)(2′OMeN₁). In some aspects, N₁ is chosen from A, C, G, or U. In some aspects, N₁ is A. In some aspects, N₁ is C. In some aspects, N₁ is G. In some aspects, N₁ is U. In some aspects, a m7(3′OMeG)(5′)ppp(5′)(2′OMeN₁) Cap 1 structure comprises a second nucleotide, N₂, which is a cap proximal nucleotide at position 2 and is chosen from A, G, C, or U (m7(3′OMeG)(5′)ppp(5′)(2′OmeN₁)N₂). In some aspects, N₂ is A. In some aspects, N₂ is C. In some aspects, N₂ is G. In some aspects, N₂ is U. In some aspects, a second nucleotide in a Cap 1 structure may comprise one or more modifications, e.g., methylation. In some aspects, a Cap 1 structure comprising a second nucleotide comprising a 2′O methylation is a Cap 2 structure. In some aspects, the RNA molecule may be enzymatically capped at the 5′ end using Vaccinia guanylyltransferase, guanosine triphosphate, and S-adenosyl-L-methionine to yield Cap 0 structure. An inverted 7-methylguanosine cap is added via a 5′ to 5′ triphosphate bridge. Alternatively, use of a 2′O-methyltransferase with Vaccinia guanylyltransferase yields the Cap 1 structure where in addition to the Cap 0 structure, the 2′OH group is methylated on the penultimate nucleotide. S-adenosyl-L-methionine (SAM) is a cofactor utilized as a methyl transfer reagent. Non-limiting examples of 5′ cap structures are those which, among other things, have enhanced binding of cap binding polypeptides, increased half-life, reduced susceptibility to 5′ endonucleases and/or reduced 5′ decapping, as compared to synthetic 5′ cap structures known in the art (or to a wild type, natural or physiological 5′ cap structure). For example, recombinant Vaccinia Virus Capping Enzyme and recombinant 2′ O- methyltransferase enzyme may create a canonical 5′-5′-triphosphate linkage between the 5′- terminal nucleotide of an mRNA and a guanine cap nucleotide wherein the cap guanine includes an N7 methylation and the 5′-terminal nucleotide of the mRNA includes a 2′-O-methyl. Such a structure is termed the Cap 1 structure. This cap results in a higher translational- competency and cellular stability and a reduced activation of cellular pro-inflammatory cytokines, as compared, e.g., to other 5′ cap analog structures known in the art. In some aspects, the 5′ terminal cap includes a cap analog, for example, a 5′ terminal cap may include a guanine analog. Exemplary guanine analogs include, but are not limited to, inosine, N1-methyl-guanosine, 2′-fluoro-guanosine, 7-deaza-guanosine, 8-oxo-guanosine, 2- amino-guanosine, LNA-guanosine, and 2-azido-guanosine. In some aspects, the capping region may include a single cap or a series of nucleotides forming the cap. In this aspect the capping region may be from 1 to 10, e.g.2-9, 3-8, 4-7, 1-5, 5-10, or at least 2, or 10 or fewer nucleotides in length. In this aspect the capping region is at least, at most, exactly, or between any two of 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides in length. In some aspects, the cap is absent. In some aspects, the first and second operational regions may range from 3 to 40, e.g., 5-30, 10-20, 15, or at least 4, or 30 or fewer nucleotides in length and may comprise, in addition to a Start and/or Stop codon, one or more signal and/or restriction sequences. In some aspects, the first and second operational regions are at least, at most, exactly, or between any two of 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40 nucleotides in length and may comprise, in addition to a Start and/or Stop codon, one or more signal and/or restriction sequences. Further examples of 5′ cap structures include, but are not limited to, glyceryl, inverted deoxy abasic residue (moiety), 4’, 5′ methylene nucleotide, 1-(beta-D-erythrofuranosyl) nucleotide, 4’-thio nucleotide, carbocyclic nucleotide, 1,5-anhydrohexitol nucleotide, L- nucleotides, alpha-nucleotide, modified base nucleotide, threo-pentofuranosyl nucleotide, acyclic 3′,4’-seco nucleotide, acyclic 3,4-dihydroxybutyl nucleotide, acyclic 3,5 dihydroxypentyl nucleotide, 3′-3′-inverted nucleotide moiety, 3′-3′-inverted abasic moiety, 3′-2′-inverted nucleotide moiety, 3′-2′-inverted abasic moiety, 1,4-butanediol phosphate, 3′- phosphoramidate, hexylphosphate, aminohexyl phosphate, 3′-phosphate, 3′phosphorothioate, phosphorodithioate, or bridging or non-bridging methylphosphonate moiety. In some aspects, the RNA molecule of the present disclosure comprises at least one 5′ cap structure. In some aspects, the RNA molecule of the present disclosure does not comprise a 5′ cap structure. In one aspect, the 5′ capping structure comprises a modified 5′ Cap 1 structure (m⁷G⁺m^3’-5’-ppp-5’-Am). In one aspect, the 5′ capping structure comprises is (3’OMe) - m₂ ^7,3’- ^OGppp (m₁ ^2’-O)ApG (Trilink). This molecule is identical to the natural RNA cap structure in that it starts with a guanosine methylated at N7, and is linked by a 5’ to 5’ triphosphate linkage to the first coded nucleotide of the transcribed RNA (in this case, an adenosine). This guanosine is also methylated at the 3’ hydroxyl of the ribose to mitigate possible reverse incorporation of the cap molecule. The 2’ hydroxyl of the ribose on the adenosine is methylated, conferring a Cap1 structure. 3. UNTRANSLATED REGIONS (UTRS) The 5′ UTR is a regulatory region situated at the 5′ end of a protein open reading frame that is transcribed into mRNA but not translated into an amino acid sequence or to the corresponding region in an RNA polynucleotide, such as an mRNA molecule. An untranslated region (UTR) may be present 5′ (upstream) of an open reading frame (5′ UTR) and/or 3′ (downstream) of an open reading frame (3′ UTR). In some aspects, the UTR is derived from an mRNA that is naturally abundant in a specific tissue (e.g., lymphoid tissue), to which the mRNA expression is targeted. In some aspects, the UTR increases protein synthesis. Without being bound by mechanism or theory, the UTR may increase protein synthesis by increasing the time that the mRNA remains in translating polysomes (message stability) and/or the rate at which ribosomes initiate translation on the message (message translation efficiency). Accordingly, the UTR sequence may prolong protein synthesis in a tissue-specific manner. In some aspects, the 5′ UTR and the 3′ UTR sequences are computationally derived. In some aspects, the 5′ UTR and the 3′ UTRs are derived from a naturally abundant mRNA in a tissue. The tissue may be, for example, liver, a stem cell or lymphoid tissue. The lymphoid tissue may include, for example, any one of a lymphocyte (e.g., a B-lymphocyte, a helper T- lymphocyte, a cytotoxic T-lymphocyte, a regulatory T-lymphocyte, or a natural killer cell), a macrophage, a monocyte, a dendritic cell, a neutrophil, an eosinophil and a reticulocyte. In some aspects, the 5′ UTR and the 3′ UTR are derived from an alphavirus. In some aspects, the 5′ UTR and the 3′ UTR are from a wild type alphavirus. 4. 5′ UTRS In some aspects, an RNA disclosed herein comprises a 5′ UTR. A 5′ UTR, if present, is located at the 5′ end and starts with the transcriptional start site upstream of the start codon of a protein encoding region. A 5′ UTR is downstream of the 5′ cap (if present), e.g. directly adjacent to the 5′ cap. The 5′ UTR may contain various regulatory elements, e.g., 5′ cap structure, stem-loop structure, and an internal ribosome entry site (IRES), which may play a role in the control of translation initiation. In some aspects, a 5′ UTR disclosed herein comprises a cap proximal sequence, e.g., as disclosed herein. In some aspects, a cap proximal sequence comprises a sequence adjacent to a 5′ cap. In some aspects, a cap proximal sequence comprises nucleotides in positions +1, +2, +3, +4, and/or +5 of an RNA polynucleotide. In some aspects, a Cap structure comprises one or more polynucleotides of a cap proximal sequence. In some aspects, a Cap structure comprises an m7 Guanosine cap and nucleotide +1 (N₁) of an RNA polynucleotide. In some aspects, a Cap structure comprises an m7 Guanosine cap and nucleotide +2 (N₂) of an RNA polynucleotide. In some aspects, a Cap structure comprises an m7 Guanosine cap and nucleotides +1 and +2 (N₁ and N₂) of an RNA polynucleotide. Those skilled in the art, reading the present disclosure, will appreciate that, in some aspects, one or more residues of a cap proximal sequence (e.g., one or more of residues +1, +2, +3, +4, and/or +5) may be included in an RNA by virtue of having been included in a cap entity that (e.g., a Cap 1 structure, etc); alternatively, in some aspects, at least some of the residues in a cap proximal sequence may be enzymatically added (e.g., by a polymerase such as a T7 polymerase). For example, in certain exemplified aspects where a (m₂ ^7,3′-O)Gppp(m^2’- ^O)ApG cap is utilized, +1 and +2 residues are the (m₂ ^7,3′-O) A and G residues of the cap, and +3, +4, and +5 residues are added by polymerase (e.g., T7 polymerase). In preferred embodiments, the nucleic acid comprises at least one heterologous 5’- UTR, wherein the at least one heterologous 5’-UTR comprises a nucleic acid sequence derived from a 5’-UTR of gene selected from any one of HSD17B4, RPL32, ASAH1, ATP5A1 , MP68, NDUFA4, NOSIP, RPL31 , SLC7A3, TUBB4B, and UBQLN2, or from a homolog, a fragment or variant of any one of these genes. In one aspect, an RNA disclosed herein comprises a 5′ UTR comprising a sequence having at least, at most, exactly, or between any two of 99%, 98%, 97%, 96%, 95%, 90%, 85%, or 80% identity to the following sequence: GAΨAGGCGGCGCAΨGAGAGAAGCCCAGACCAAΨΨACCΨACCCAAA. In another embodiment, the 5’ UTR comprises a sequence having at least, at most, exactly, or between any two of 99%, 98%, 97%, 96%, 95%, 90%, 85%, or 80% identity to the following sequence: GAAΨAAAC ΨAGΨAΨΨCΨΨ CΨGGΨCCCCA CAGACΨCAGA GAGAACCCGC CACC. 5.3′ UTRS In some aspects, an RNA disclosed herein comprises a 3′ UTR. A 3′ UTR, if present, is situated downstream of a protein coding sequence open reading frame, e.g., downstream of the termination codon of a protein-encoding region. A 3′ UTR is typically the part of an mRNA which is located between the protein coding sequence and the poly-A tail of the mRNA. Thus, in some aspects, the 3′ UTR is upstream of the poly-A sequence (if present), e.g. directly adjacent to the poly-A sequence. The 3′ UTR may be involved in regulatory processes including transcript cleavage, stability and polyadenylation, translation, and mRNA localization. A 3′ UTR may also comprise elements, which are not encoded in the template, from which an RNA is transcribed, but which are added after transcription during maturation, e.g. a poly-A tail. A 3′ UTR of the mRNA is not translated into an amino acid sequence. In some aspects, an RNA disclosed herein comprises a 3′ UTR comprising an F element and/or an I element. In some aspects, a 3′ UTR or a proximal sequence thereto comprises a restriction site. In some aspects, an RNA disclosed herein comprises a 3′ UTR comprising a sequence having at least, at most, exactly, or between any two of 99%, 98%, 97%, 96%, 95%, 90%, 85%, or 80% identity to CΨCGAGCΨGGΨ ACΨGCAΨGCA CGCAAΨGCΨA GCΨGCCCCΨΨ ΨCCCGΨCCΨG GGΨACCCCGA GΨCΨCCCCCG ACCΨCGGGΨC CCAGGΨAΨGC ΨCCCACCΨCC ACCΨGCCCCA CΨCACCACCΨ CΨGCΨAGΨΨC CAGACACCΨC CCAAGCACGC AGCAAΨGCAG CΨCAAAACGC ΨΨAGCCΨAGC CACACCCCCA CGGGAAACAG CAGΨGAΨΨAA CCΨΨΨAGCAA ΨAAACGAAAG ΨΨΨAACΨAAG CΨAΨACΨAAC CCCAGGGΨΨG GΨCAAΨΨΨCG ΨGCCAGCCAC ACCCΨGGAGC ΨAGC. In preferred embodiments, the nucleic acid comprises at least one heterologous 3’-UTR, wherein the at least one heterologous 3’-UTR comprises a nucleic acid sequence derived from a 3’-UTR of a gene selected from PSMB3, ALB7, alpha-globin (referred to as “muag”), CASP1 , COX6B1 , GNAS, NDUFA1 and RPS9, or from a homolog, a fragment or variant of any one of these genes. 6. POLY-A TAIL In some aspects, RNA molecules disclosed herein comprise a poly-adenylate (poly-A) sequence. In some aspects, a poly-A sequence is situated downstream of a 3′ UTR, e.g., adjacent to a 3′ UTR. A “poly-A tail” or “poly-A sequence” refers to a stretch of consecutive adenine residues, which may be attached to the 3’ end of the RNA molecule. Poly-A sequences are known to those of skill in the art and may follow the 3′ UTR in the RNA molecules described herein. The poly-A tail may increase the half-life of the RNA molecule. RNA molecules disclosed herein may have a poly-A sequence attached to the free 3′- end of the RNA by a template-independent RNA polymerase after transcription or a poly-A sequence encoded by DNA and transcribed by a template-dependent RNA polymerase. In some aspects, a poly-A sequence is attached during RNA transcription, e.g., during preparation of in vitro transcribed RNA, based on a DNA template comprising repeated dT nucleotides (deoxythymidylate) in the strand complementary to the coding strand. In some aspects, the poly-A sequence contained in an RNA polynucleotide described herein essentially consists of adenosine nucleotides, but is interrupted by a random sequence of the four nucleotides (A, C, G, U). Such a random sequence may be at least, at most, exactly, or between any two of 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50 nucleotides in length. In some aspects, no nucleotides other than adenosine nucleotides flank a poly-A sequence at its 3′-end, e.g., the poly-A sequence, is not masked or followed at its 3′-end by a nucleotide other than adenosine. The poly-A sequence may be of any length. In some aspects, the poly-A tail may include 5 to 300 nucleotides in length. In some aspects, the RNA molecule includes a poly-A tail that comprises, essentially consists of, or consists of a sequence of about 25 to about 400 adenosine nucleotides, a sequence of about 50 to about 400 adenosine nucleotides, a sequence of about 50 to about 300 adenosine nucleotides, a sequence of about 50 to about 250 adenosine nucleotides, a sequence of about 60 to about 250 adenosine nucleotides, or a sequence of about 40 to about 100 adenosine nucleotides. In some aspects, the poly-A tail comprises, essentially consists of, or consists of at least, at most, exactly, or between any two of 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200, 205, 210, 215, 220, 225, 230, 235, 240, 245, 250, 255, 260, 265, 270, 275, 280, 285, 290, 295, 300, 305, 310, 315, 320, 325, 330, 335, 340, 345, 350, 355, 360, 365, 370, 375, 380, 385, 390, 395, 400, 405, 410, 415, 420, 425, 430, 435, 440, 445, 450, 455, 460, 465, 470, 475, 480, 485, 490, 495, or 500 adenosine nucleotides. In this context, “essentially consists of” means that most nucleotides in the poly-A sequence, typically at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% by number of nucleotides in the poly-A sequence are adenosine nucleotides, but permits that remaining nucleotides are nucleotides other than adenosine nucleotides, such as uridine, guanosine, or cytosine. In this context, “consists of” means that all nucleotides in the poly-A sequence, e.g., 100% by number of nucleotides in the poly-A sequence, are adenosine nucleotides. In some aspects, the RNA molecule includes a poly-A tail that includes a sequence of greater than 30 adenosine nucleotides. In some aspects, the RNA molecule includes a poly-A tail that includes about 40 adenosine nucleotides. In some aspects, the RNA molecule includes a poly-A tail that includes about 80 adenosine nucleotides. In some aspects, the 3’ poly-A tail has a stretch of at least 10 consecutive adenosine residues and at most 300 consecutive adenosine residues. In some specific aspects, the RNA molecule includes about 40 consecutive adenosine residues. In some aspects, the RNA molecule includes about 80 consecutive adenosine residues. Poly-A tails may play key regulatory roles in enhancing translation efficiency and regulating the efficiency of mRNA quality control and degradation. Short sequences or hyperpolyadenylation may signal for RNA degradation. Some designs include a poly-A tails of about 40 adenosine nucleotides, about adenosine nucleotides. F. SELF-AMPLIFYING RNA (SARNA) In some aspects, the RNA molecule may be an saRNA. “Self-amplifying RNA,” “self- amplifying RNA,” “self-replicating” and “replicon” may all be used interchangeably, and refer to RNA with the ability to replicate itself. Self-amplifying RNA molecules may be produced by using replication elements derived from, e.g. alphaviruses, and substituting the structural viral polypeptides with a nucleotide sequence encoding a polypeptide of interest. A self-amplifying RNA molecule is typically a positive-strand molecule that may be directly translated after delivery to a cell, and this translation provides an RNA-dependent RNA polymerase which then produces both antisense and sense transcripts from the delivered RNA. The delivered RNA leads to the production of multiple daughter RNA molecules. These daughter RNA molecules, as well as collinear subgenomic transcripts, may be translated themselves to provide in situ expression of an encoded gene of interest, e.g., a viral antigen, or may be transcribed to provide further transcripts with the same sense as the delivered RNA which are translated to provide in situ expression of the antigen. The overall result of this sequence of transcriptions is an amplification in the number of the introduced saRNA molecules and so the encoded gene of interest, e.g., a viral antigen, becomes a major polypeptide product of the cells. In some aspects, the self-amplifying RNA includes at least one or more genes including any one of viral replicases, viral proteases, viral helicases and other nonstructural viral proteins, or combination thereof. In some aspects, the self-amplifying RNA may also include 5’- and 3’- end tractive replication sequences, and optionally a heterologous sequence that encodes a desired amino acid sequence (e.g., an antigen of interest). A subgenomic promoter that directs expression of the heterologous sequence may be included in the self-amplifying RNA. Optionally, the heterologous sequence (e.g., an antigen of interest) may be fused in frame to other coding regions in the self-amplifying RNA and/or may be under the control of an internal ribosome entry site (IRES). In some aspects, a self-amplifying RNA molecule described herein encodes (i) an RNA-dependent RNA polymerase that may transcribe RNA from the self-amplifying RNA molecule and (ii) a polypeptide of interest, e.g., a viral antigen. In some aspects, the polymerase may be an alphavirus replicase, e.g., including any one of alphavirus protein nsP1, nsP2, nsP3, nsP4, and any combination thereof. G. RNA ENCAPSULATION The RNA in an RNA product solution may be encapsulated, and the RNA solution may further comprise at least one encapsulating agent. In one aspect, the encapsulating agent comprises a lipid, a lipid nanoparticle (LNP), lipoplexes, polymeric particles, polyplexes, and monolithic delivery systems, and a combination thereof. In some aspects, 1, 2, 3, 4, 5, or more of the foregoing elements may be excluded as an encapsulating agent. In some aspects, LNPs may be designed to protect RNA molecules (e.g., saRNA, mRNA) from extracellular RNases and/or may be engineered for systemic delivery of the RNA to target cells. In some aspects, such LNPs may be particularly useful to deliver RNA molecules (e.g., mRNA, saRNA, modRNA) when RNA molecules are intravenously administered to a subject in need thereof. In some aspects, such LNPs may be particularly useful to deliver RNA molecules (e.g., saRNA, mRNA) when RNA molecules are intramuscularly administered to a subject in need thereof. In one aspect, the RNA in the RNA solution is at a concentration of < 1 mg/mL. In another aspect, the RNA is at a concentration of at least about 0.05 mg/mL. In another aspect, the RNA is at a concentration of at least about 0.5 mg/mL. In another aspect, the RNA is at a concentration of at least about 1 mg/mL. In another aspect, the RNA concentration is from about 0.05 mg/mL to about 0.5 mg/mL. In another aspect, the RNA is at a concentration of at least 10 mg/mL. In another aspect, the RNA is at a concentration of at least 50 mg/mL. In some aspects, the RNA is at a concentration of at least, at most, exactly, or between any two of about 0.05 mg/mL, 0.5 mg/mL, 1 mg/mL, 10 mg/mL, 50 mg/mL, 75 mg/mL, 100 mg/mL, 150 mg/mL, 200 mg/mL, 250 mg/mL, 300 mg/mL, 400 mg/mL, or more. The present disclosure provides for an RNA solution and lipid preparation mixture or compositions thereof comprising at least one RNA encoding, e.g., an antigen (e.g., a hMPV F protein mutant and/or an antigen derived from PIV1 and/or an antigen derived from PIV3) complexed with, encapsulated in, and/or formulated with one or more lipids, and forming lipid nanoparticles (LNPs), liposomes, lipoplexes and/or nanoliposomes. In some aspects, the composition comprises a lipid nanoparticle. Preferably, the LNP comprises (i) at least one cationic lipid; (ii) at least one neutral lipid; (iii) at least one steroid or steroid analogue, preferably cholesterol; and (iv) at least one polymer conjugated lipid, preferably a PEG-lipid; wherein (i) to (iv) are in a molar ratio of about 20-60% cationic lipid, 5-25% neutral lipid, 25-55% sterol, and 0.5-15% polymer conjugated lipid. In some aspects, the lipid nanoparticles comprise one or more cationic lipids. In one aspect, the lipid nanoparticles comprise (4-hydroxybutyl)azanediyl)bis(hexane-6,1-diyl)bis(2- hexyldecanoate) (ALC-0315), having the formula: In embodiments, the cationic lipid is present in the LNP in an amount from about 30 to about 70 mole percent. In one embodiment, the cationic lipid is present in the LNP in an amount from about 40 to about 60 mole percent, such as about 40, 41 , 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 , 52, 53, 54, 55, 56, 57, 58, 59 or 60 mole percent, respectively. In embodiments, the cationic lipid is present in the LNP in an amount from about 47 to about 48 mole percent, such as about 47.0, 47.1 , 47.2, 47.3, 47.4, 47.5, 47.6, 47.7, 47.8, 47.9, 50.0 mole percent, respectively, wherein 47.7 mole percent are particularly preferred. In some embodiments, the cationic lipid is present in a ratio of from about 20mol% to about 70 or 75mol% or from about 45 to about 65mol% or about 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, or about 70mol% of the total lipid present in the LNP. In further embodiments, the LNPs comprise from about 25% to about 75% on a molar basis of cationic lipid, e.g., from about 20 to about 70%, from about 35 to about 65%, from about 45 to about 65%, about 60%, about 57.5%, about 57.1%, about 50% or about 40% on a molar basis (based upon 100% total moles of lipid in the lipid nanoparticle). In some embodiments, the ratio of cationic lipid to nucleic acid (e.g. coding RNA or DNA) is from about 3 to about 15, such as from about 5 to about 13 or from about 7 to about 11. In some aspects, the LNPs comprise a polymer conjugated lipid. The term “polymer conjugated lipid” refers to a molecule comprising both a lipid portion and a polymer portion. An example of a polymer conjugated lipid is a pegylated lipid. The term “pegylated lipid” refers to a molecule comprising both a lipid portion and a polyethylene glycol portion. Pegylated lipids are known in the art and include 1-(monomethoxy-polyethyleneglycol)-2,3-dimyristoylglycerol (PEG-s-DMG), 2-[(polyethylene glycol)-2000]-N,N-ditetradecylacetamide, and the like. In some aspects, the lipid nanoparticles comprise a polymer conjugated lipid. In one aspect, the lipid nanoparticle comprises 2-[(polyethylene glycol)-2000]-N,N- ditetradecylacetamide (ALC-0159), having the formula: In various aspects, the molar ratio of the cationic lipid to the pegylated lipid ranges from about 100:1 to about 20:1, e.g., from about 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 55:1, 60:1, 65:1, 70:1, 75:1, 80:1, 85:1, 90:1, 95:1, or 100:1, or any range or value derivable therein. In certain aspects, the PEG-lipid is present in the LNP in an amount from about 1 to about 10 mole percent (mol %) (e.g., at least, at most, exactly, or between any two of 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 mol %), relative to the total lipid content of the nanoparticle. In some embodiments, LNPs include less than about 3, 2, or 1 mole percent of PEG or PEG-modified lipid, based on the total moles of lipid in the LNP. In further embodiments, LNPs comprise from about 0.1% to about 20% of the PEG-modified lipid on a molar basis, e.g., about 0.5 to about 10%, about 0.5 to about 5%, about 10%, about 5%, about 3.5%, about 3%, about 2,5%, about 2%, about 1.5%, about 1 %, about 0.5%, or about 0.3% on a molar basis (based on 100% total moles of lipids in the LNP). In preferred embodiments, LNPs comprise from about 1.0% to about 2.0% of the PEG-modified lipid on a molar basis, e.g., about 1.2 to about 1.9%, about 1.2 to about 1.8%, about 1.3 to about 1.8%, about 1.4 to about 1.8%, about 1.5 to about 1.8%, about 1.6 to about 1.8%, in particular about 1.4%, about 1.5%, about 1.6%, about 1.7%, about 1.8%, about 1.9%, most preferably 1.7% (based on 100% total moles of lipids in the LNP). In some aspects, provided RNA molecules (e.g., mRNA, saRNA, modRNA) may be formulated with LNPs. In some aspects, the lipid nanoparticles may have a mean diameter of about 1 to 500 nm. In some aspects, the lipid nanoparticles have a mean diameter of from about 30 nm to about 150 nm, from about 40 nm to about 150 nm, from about 50 nm to about 150 nm, from about 60 nm to about 130 nm, from about 70 nm to about 110 nm, from about 70 nm to about 100 nm, from about 80 nm to about 100 nm, from about 90 nm to about 100 nm, from about 70 to about 90 nm, from about 80 nm to about 90 nm, from about 70 nm to about 80 nm, or at least, at most, exactly, or between any two of 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, 105 nm, 110 nm, 115 nm, 120 nm, 125 nm, 130 nm, 135 nm, 140 nm, 145 nm, or 150 nm, and are substantially non-toxic. The term “mean diameter” refers to the mean hydrodynamic diameter of particles as measured by dynamic laser light scattering (DLS) with data analysis using the so-called cumulant algorithm, which provides as results the so-called Z-average with the dimension of a length, and the polydispersity index (PI), which is dimensionless (Koppel, D., J. Chem. Phys.57, 1972, pp 4814-4820, ISO 13321). Here, “mean diameter,” “diameter,” or “size” for particles is used synonymously with this value of the Z-average. LNPs described herein may exhibit a polydispersity index less than about 0.5, less than about 0.4, less than about 0.3, or about 0.2 or less. By way of example, the LNPs may exhibit a polydispersity index of at least, at most, exactly, or between any two of 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, or 0.5. The polydispersity index is, in some aspects, calculated based on dynamic light scattering measurements by the so-called cumulant analysis as mentioned in the definition of the “average diameter.” Under certain prerequisites, it may be taken as a measure of the size distribution of an ensemble of nanoparticles. In certain aspects, nucleic acids, when present in the lipid nanoparticles, are resistant in aqueous solution to degradation with a nuclease. Lipid nanoparticles comprising nucleic acids and their method of preparation are disclosed in, e.g., U.S. Patent Publication Nos. 2004/0142025, 2007/0042031 and PCT Pub. Nos. WO 2013/016058 and WO 2013/086373, the full disclosures of which are herein incorporated by reference in their entirety for all purposes. H. EXAMPLES The invention is further described by the following illustrative examples. The examples do not limit the invention in any way. They merely serve to clarify the invention. EXAMPLE 1: DESIGN AND PREPARATION OF HMPV B F PROTEIN MUTANTS This example illustrates the design and preparation of various hMPV B F protein mutants, which include a fibritin foldon trimerization domain and introduced amino acid mutations, such as engineered interprotomer disulfide bond mutations. Exemplary hMPV B F protein mutants, each of which is identified by a unique identifier, such as hMPV0178, hMPV0179, etc., are provided in Table 2. Each of these mutants is designed and prepared based on the amino acid sequence set forth in SEQ ID NO:32. Amino acid residues 1-489 of the sequence of SEQ ID NO:32 are identical to amino acid residues 1- the amino acid sequences of these exemplary F protein mutants are identical except for the introduced amino acid mutations as noted for each mutant listed in Table 2. Each of these hMPV F protein mutants comprises two separate polypeptide chains. One of the polypeptide chains, the F2 polypeptide, comprises amino acids 19-102 of SEQ ID NO:32 except for the introduced mutations as noted. The other polypeptide chain comprises the F1 polypeptide (residues 103-489) linked to a foldon trimerization domain (residues 494-520) via a GGGS linker (residues 490-493). The signal peptide (residues 1-18) of SEQ ID NO:32 were cleaved from the F0 precursor during the expression process. Table 2. Exemplary hMPV B F Protein Mutants Comprising Engineered interprotomer Disulfide Mutations Mutant ID Mutations Amino Acid Sequence (residues 103-489 for F1 polypeptide and residues 19-102 for F2 polypeptide) hMPV178 T69C-Q195C F1 (SEQ ID NO:9): FVLGAIALGVATAAAVTAGIAIAKTIRLESEVNAIKGALKTTN EAVSTLGNGVRVLATAVRELKEFVSKNLTSAINKNKCDIAD LKMAVSFSCFNRRFLNVVRQFSDNAGITPAISLDLMNDAE LARAVSYMPTSAGQIKLMLENRAMVRRKGFGILIGVYGSS VIYMVQLPIFGVINTPCWIIKAAPSCSEKDGNYACLLREDQ GWYCKNAGSTVYYPNEKDCETRGDHVFCDTAAGINVAE QSRECNINISTTNYPCKVSTGRHPISMVALSPLGALVACYK GVSCSIGSNQVGIIKQLPKGCSYITNQDADTVTIDNTVYQL SKVEGEQHVIKGRPVSNSFDPIRFPEDQFNVALDQVFESI ENSQALVDQSNKILNSAEKGNT F2 (SEQ ID NO:10): LKESYLEESCSTITEGYLSVLRTGWYTNVFTLEVGDVENL TCTDGPSLIKCELDLTKSALRELKTVSADQLAREEQIENPR QSR hMPV179 E80C-D224C F1 (SEQ ID NO:11): FVLGAIALGVATAAAVTAGIAIAKTIRLESEVNAIKGALKTTN EAVSTLGNGVRVLATAVRELKEFVSKNLTSAINKNKCDIAD LKMAVSFSQFNRRFLNVVRQFSDNAGITPAISLDLMNCAE LARAVSYMPTSAGQIKLMLENRAMVRRKGFGILIGVYGSS VIYMVQLPIFGVINTPCWIIKAAPSCSEKDGNYACLLREDQ GWYCKNAGSTVYYPNEKDCETRGDHVFCDTAAGINVAE QSRECNINISTTNYPCKVSTGRHPISMVALSPLGALVACYK GVSCSIGSNQVGIIKQLPKGCSYITNQDADTVTIDNTVYQL SKVEGEQHVIKGRPVSNSFDPIRFPEDQFNVALDQVFESI ENSQALVDQSNKILNSAEKGNT F2 (SEQ ID NO:12): LKESYLEESCSTITEGYLSVLRTGWYTNVFTLEVGDVENL TCTDGPSLIKTELDLTKSALRCLKTVSADQLAREEQIENPR QSR hMPV180 A211C-M250C F1 (SEQ ID NO:13): FVLGAIALGVATAAAVTAGIAIAKTIRLESEVNAIKGALKTTN EAVSTLGNGVRVLATAVRELKEFVSKNLTSAINKNKCDIAD LKMAVSFSQFNRRFLNVVRQFSDNCGITPAISLDLMNDAE LARAVSYMPTSAGQIKLMLENRACVRRKGFGILIGVYGSS VIYMVQLPIFGVINTPCWIIKAAPSCSEKDGNYACLLREDQ GWYCKNAGSTVYYPNEKDCETRGDHVFCDTAAGINVAE QSRECNINISTTNYPCKVSTGRHPISMVALSPLGALVACYK GVSCSIGSNQVGIIKQLPKGCSYITNQDADTVTIDNTVYQL SKVEGEQHVIKGRPVSNSFDPIRFPEDQFNVALDQVFESI ENSQALVDQSNKILNSAEKGNT F2 (SEQ ID NO:14): LKESYLEESCSTITEGYLSVLRTGWYTNVFTLEVGDVENL TCTDGPSLIKTELDLTKSALRELKTVSADQLAREEQIENPR QSR hMPV181 T337C-T423C F1 (SEQ ID NO:15): FVLGAIALGVATAAAVTAGIAIAKTIRLESEVNAIKGALKTTN EAVSTLGNGVRVLATAVRELKEFVSKNLTSAINKNKCDIAD LKMAVSFSQFNRRFLNVVRQFSDNAGITPAISLDLMNDAE LARAVSYMPTSAGQIKLMLENRAMVRRKGFGILIGVYGSS VIYMVQLPIFGVINTPCWIIKAAPSCSEKDGNYACLLREDQ GWYCKNAGSTVYYPNEKDCETRGDHVFCDCAAGINVAE QSRECNINISTTNYPCKVSTGRHPISMVALSPLGALVACYK GVSCSIGSNQVGIIKQLPKGCSYITNQDADTVTIDNCVYQL SKVEGEQHVIKGRPVSNSFDPIRFPEDQFNVALDQVFESI ENSQALVDQSNKILNSAEKGNT F2 (SEQ ID NO:16): LKESYLEESCSTITEGYLSVLRTGWYTNVFTLEVGDVENL TCTDGPSLIKTELDLTKSALRELKTVSADQLAREEQIENPR QSR hMPV182 G111C-E323C F1 (SEQ ID NO:17): FVLGAIALCVATAAAVTAGIAIAKTIRLESEVNAIKGALKTTN EAVSTLGNGVRVLATAVRELKEFVSKNLTSAINKNKCDIAD LKMAVSFSQFNRRFLNVVRQFSDNAGITPAISLDLMNDAE LARAVSYMPTSAGQIKLMLENRAMVRRKGFGILIGVYGSS VIYMVQLPIFGVINTPCWIIKAAPSCSEKDGNYACLLREDQ GWYCKNAGSTVYYPNCKDCETRGDHVFCDTAAGINVAE QSRECNINISTTNYPCKVSTGRHPISMVALSPLGALVACYK GVSCSIGSNQVGIIKQLPKGCSYITNQDADTVTIDNTVYQL SKVEGEQHVIKGRPVSNSFDPIRFPEDQFNVALDQVFESI ENSQALVDQSNKILNSAEKGNT F2 (SEQ ID NO:18): LKESYLEESCSTITEGYLSVLRTGWYTNVFTLEVGDVENL TCTDGPSLIKTELDLTKSALRELKTVSADQLAREEQIENPR QSR EXAMPLE 2. HMPV B F PROTEIN MUTANT EXPRESSION VECTOR CONSTRUCTION A nucleic acid molecule encoding the consensus truncated hMPV B F0 polypeptide set forth in SEQ ID NO: 32 is mutated using standard molecular biology techniques to encode a precursor polypeptide for a hMPV F mutant having the introduced amino acid mutations disclosed in example 1. The structure and components of the precursor polypeptide are set forth in Figure 1A and SEQ ID NO: 32. The precursor polypeptide comprises of a signal peptide (residues 1-18), F2 polypeptide (residues 19-102), F1 polypeptide (residues 103-489), T4 fibritin foldon (residues 494-520), PreScission cleavage site (residues 524-531), Strep Tag II (residues 535-542), and linker sequences (residues 490-493, 521-523, 532-534, 543-546). The protein sequence of SEQ ID NO: 32 is submitted for mammalian codon optimization by Genscript (Piscataway, NJ). The nucleotide sequence is introduced into a commercially available expression vector, pcDNA3.1/Zeo(+) (ThermoFisher Scientific, Waltham, MA) that has been modified to encode the CAG promoter (Yamamura et al., . Gene, 108(2), 193-199, 1991) in place of the CMV promoter. Double stranded DNA fragments are purchased from Integrated DNA Technologies (Coralville, IA). DNA fragments of the mutagenized F allele not synthesized are generated and amplified by polymerase chain reaction (PCR) with Phusion Flash High-Fidelity PCR Master Mix (ThermoFisher Scientific). Following purification of the linearized expression vector digested using BamHI and NotI, gene fragments of the mutagenized F allele are inserted into the expression vector with NEBuilder HiFi DNA Assembly Kit (New England Biolabs, Ipswich, MA). The presence of the intended sequence is confirmed by Sanger DNA sequencing. Plasmid DNA for transfection into ExpiCHO cells is purified with the Qiagen Plasmid Plus Midi Kit (Qiagen, Valencia, CA). For all commercial kits or reagents, procedures are performed according to the manufacturer’s protocol. EXAMPLE 3. TRANSFECTION OF HMPV B F PROTEIN MUTANTS Proteins for hMPV B F mutant evaluation are produced by transient transfection of ExpiCHO cells (ThermoFisher Scientific) with DNA plasmids assembled and prepared as described in Example 2. Transient transfections are carried out according to the manufacturer’s protocol. On day 5 post transfection, the cultures are centrifuged, and supernatants are separated from cell pellets. The crude cell supernatants are used for in vitro assays described herein. EXAMPLE 4. EXPRESSION AND CONFORMATIONAL INTEGRITY OF HMPV B F PROTEIN MUTANTS The OCTET HTX (Sartorius, Göttingen, Germany) instrument was used to evaluate the expression and conformational integrity for each mutant. All measurements were conducted at 30 °C temperature in 96-well black plates (Corning, Corning, NY) with a final volume of 240 µL per well at a constant agitation rate of 1000 RPM. 4A: Quantitation of Expression of hMPV B F Protein Mutants Crude cell supernatant was used to quantitate the expression levels of hMPV B F protein mutants. Anti-Murine IgG Quantitation (AMQ) Biosensors (Sartorius) were first equilibrated in phosphate-buffered saline (PBS), 1% bovine serum albumin (BSA) (PB) before being dipped into more PB to establish the initial baseline. Biosensors were incubated with a mouse Strep·Tag® II monoclonal antibody (mAb) (Novagen, EMD Millipore Corporation, Temecula, CA) before being equilibrated in PB to establish the experimental baseline. The mAb bound biosensors were then dipped into crude cell culture supernatant for 2.5 minutes. OCTET data analysis software (version 13.0, Sartorius) is used to generate a standard curve from a serially diluted purified protein reference within the same assay. Titers for protein mutants were then determined based on the standard curve. 4B: Conformational Integrity of hMPV B F Protein Mutants by a thermal stress experiment Conformation integrity of hMPV B F protein mutants are evaluated by a thermal stress experiment. Crude cell culture supernatants are normalized based on the results of the titer quantitation and then incubated for 1 hour at room temperature and two higher temperatures. For the testing of hMPV B single mutants, the two temperatures are 53 °C and 56 °C. Some additional mutants are stressed at higher temperature, 56 °C, and 63 °C. After the incubation, the protein mutants are probed with prefusion specific monoclonal antibody hMPV-2 by OCTET HTX. Anti-Human IgG Fc Capture (AHC) biosensors are first equilibrated in PB before being dipped into more PB for to establish the initial baseline. Biosensors are incubated with hMPV-2 before being equilibrated in PB to establish the experimental baseline. The mAb- bound biosensors are then dipped into the thermal stresses cell culture supernatants for 5 minutes. The kinetics analysis is done by OCTET data analysis software (version 12.2, Sartorius) based on curve fitting of the entire associate step. 4C: Conformational Integrity of hMPV B F Protein Mutants by binding response to specific mAb Conformation integrity of hMPV B F protein mutants were evaluated by quantifying binding responses with prefusion specific monoclonal antibody at room temperature. Crude cell culture supernatants were normalized based on the results of the titer quantitation and then incubated for 1 hour at room temperature. After the incubation, the protein mutants were probed with prefusion specific mAb hMPV-2 by OCTET HTX. Anti-Human IgG Fc Capture (AHC) biosensors were first equilibrated in PB before being dipped into more PB for to establish the initial baseline. Biosensors were incubated with hMPV-2 before being equilibrated in PB to establish the experimental baseline. The mAb-bound biosensors were then dipped into the cell culture supernatants for 10 minutes. The kinetics analysis was done by OCTET data analysis software (version 13.0, Sartorius) based on curve fitting of the first 5 minutes of the associate step. The results are presented in Table 3. While the expression data suggest low expression of the new design, hMPV178 and hMPV181 clearly demonstrated binding responses with the hMPV- 2 mAb at about 2.5-fold lower compared with WT control. The results are presented in Table 3. Table 3. Protein expression and conformational integrity of hMPV B F protein mutants. Response Shift with hMPV-2 mAb Mutant ID Protein expression (mg/L) No stress (nm) WT 5.28 0.758 hMPV178 0.78 0.318 hMPV179 0.43 -0.019 hMPV180 0.45 -0.003 hMPV181 0.66 0.298 hMPV182 0.62 0.026 EXAMPLE 5: NUCLEOSIDE-MODIFIED MESSENGER RNA (MODRNA) PRODUCTION FOR IMMUNOGENICITY STUDIES DNA plasmids encoding the full-length F antigens with various engineered mutations were constructed using standard molecular biology techniques. The sequence includes expression elements, such as 5’-untranslated region (5’-UTR), 3’-UTR, and poly-adenosine (poly-A) tail, and a Homo sapiens-codon optimized sequence encoding a full-length F protein with engineered mutations (Figure 1B). The same mutant ID is used for modRNA and protein mutant when they comprise the same mutations. However, the structure of the exemplified protein mutant and of the exemplified protein mutant encoded by a modRNA are different as the exemplified modRNAs encode a full length protein mutant comprising the ectodomain, transmembrane domain and cytoplasmic domain of the F protein while the exemplified protein mutants comprise a truncated ectodomain and no intracellular or transmembrane domain. Plasmids were amplified in Escherichia coli and purified using Qiagen Plasmid Maxi kits (Qiagen). Plasmid DNA was linearized immediately following the 3′ end poly-A tail of the modRNA sequence by restriction enzyme digestion and purified by phenol-chloroform. Linearized DNA templates were transcribed into RNA using T7 polymerase, native and N1- methylpseudouridine (mψU) ribonucleotides, and co-transcriptionally capped using Clean Cap reagent (Trilink). RNA in-vitro transcription reaction was stopped by addition of Turbo DNAse (Thermo Fisher) to digest template DNA and modRNA was purified by LiCl precipitation. EXAMPLE 6: modRNA FORMULATION INTO mRNA-LIPID-NANOPARTICLE (modRNA- LNP) FOR IMMUNOGENICITY STUDIES modRNA-LNPs were formulated by combining a modRNA containing aqueous phase and a lipid containing organic phase using a T-mixer. The organic phase was prepared by solubilizing a mixture of ionizable lipid, phospholipid, polyethylene glyco-lipid, and cholesterol at a pre-determined ratio in ethanol. The organic phase and aqueous phase were mixed by syringe pumps. The resultant solution was dialyzed against 10 mM Tris buffer (pH 7.4). Post- dialysis solution was concentrated and spiked with cryo-protectant to a final modRNA-LNP solution. EXAMPLE 7: PREFUSION-STABILIZED, FULL-LENGTH HMPV B F MUTANTS EXPRESSED THROUGH MODRNA ELICIT NEUTRALIZING RESPONSES IN MICE This murine study aimed to evaluate immunogenicity of selected hMPV B F mutants with engineered disulfide mutations expressed through modRNA. Formulated modRNA-LNPs were prepared as described in Example 5 and 6. Female Balb/c mice were immunized with 0.5 µg of LNP-formulated modRNA encoding either full-length hMPV B F WT (SEQ ID NO:40), mutant hMPV178, hMPV180, or hMPV181. Immunizations were given intramuscularly at weeks 0 and 3 (Table 4). Post-dose 1 (PD1, week 3) and post-dose 2 (PD2, week 5) sera were evaluated in an hMPV neutralization assay as described with minor modifications (Eyles et al., 2013, J Inf Dis.208(2):319-29). Briefly, neutralizing titers were determined as the serum dilution factor resulting in a 50% reduction in infectious units. Results are reported as the geometric mean titer from 10 mice per group. Overall, all hMPV B F modRNAs tested elicited a neutralizing response following two immunizations in mice compared with the saline reference (Table 5, Figure 2). At 0.5 µg dose level, compared to hMPV B WT, mutant hMPV180 and hMPV181 showed comparable or lower neutralizing antibody titers, whereas hMPV178 demonstrated a 5-fold higher neutralizing response. The result suggests that hMPV178 is the more immunogenic forms of hMPV B prefusion F antigen with engineered interprotomer disulfide mutations encoded from modRNA. Table 4. Immunization schedule of the murine immunogenicity study comparing full-length hMPV B F mutants encoded from modRNA. hMPV B F mutant 0.5 µg modRNA-LNP modRNA dose Vaccination Weeks 0, 3 Bleed Weeks 3 (PD1) 5 (PD2) Table 5. Geometric mean of 50% neutralizing titers of Balb/c mice following two immunizations with modRNA-LNP of hMPV B F mutants.^ ^ 0.5 µg modRNA-LNP Mutant ID^ GMT WT 190 hMPV178 950 hMPV180 48 hMPV181 291 Saline 20 EXAMPLE 8: IN VITRO EXPRESSION (IVE) IMAGING ASSAY FOR HMPV B ANTIGEN SCREENING ModRNA encoding hMPV B antigens were prepared as described in Example 5 and 6 above. To characterize hMPV B antigens encoded from modRNA, an in vitro expression (IVE) imaging assay was performed in HeLa cells. Cells were plated in 384 well PDL coated imaging plates (PerkinElmer) and transfected with modRNAs formulated with Lipofectamine MessengerMAX (Thermo Fisher Scientific). ModRNAs encoded full-length wild type (WT) hMPV B F protein or full-length hMPV B F protein mutant hMPV178, hMPV179, hMPV180, hMPV181 and hMPV182. ModRNAs were diluted in Opti-MEM (Thermo Fisher Scientific) media to create an 11 point 2-fold dilution series for each construct. Expression of hMPV B F protein was examined at 22 hours post transfection by immunofluorescence imaging using hMPV-2 mAb, which specifically binds hMPV F in its prefusion form. To image the plate, cells were fixed with 4% paraformaldehyde, washed, and blocked with 6% BSA (Fraction V). Subsequently, plates were incubated with hMPV-2 mAb at 0.4 mg/ml in DPBS containing 6% BSA overnight at 4 °C, followed by Dulbecco's Phosphate-Buffered Saline (DPBS) wash and anti-human AlexaFluor-488 labeled secondary antibody (0.2 mg/ml) incubation for 2 hours at RT. Hoechst nuclear stain is included at 0.2 mg/ml to allow cell count. The plates were subjected to final washes by DPBS to remove excess secondary antibody before imaging on the Opera Phenix High Content Imager. The images were analyzed with Signals Image Artist software and multiple endpoints were calculated, including MFI (mean fluorescence intensity), cell count (as a measure of toxicity/cell death) and %hMPV B F positive cells. For the percent hMPV B F positive cells readout, WT hMPV B F modRNA at 25 ng/well was used as the 100% control and Lipofectamine MessengerMax alone without modRNA was used as the negative control. EC₅₀ curves were generated using Signals GeneData Screener software. Mean EC₅₀ values of the percent hMPV B F positive cells readout were reported in Table 6 below. When expressed as full-length, membrane bound proteins through modRNA- LNP, all of the interprotomer disulfide bond designs demonstrated expression as detected by IVE. Mutant hMPV178 and hMPV181 showed comparable or slightly better EC₅₀ than WT based on hMPV-2 mAb staining. Overall, the in vitro data indicates that hMPV178 and hMPV181 are the most promising of the tested constructs. Table 6: EC₅₀ of hMPV B F antigens IVE in HeLa measured by hMPV-2 mAb Mean EC Antigen ID Mutation ₅₀ SD Ns (ng/ml) hMPV163 WT 2.62 0.604 9 hMPV178 T69C-Q195C 1.76 1.31 3 hMPV179 E80C-D224C 25 0 3 hMPV180 A211C-M250C 17.25 13.4 3 hMPV181 T337C-T423C 2.01 0.327 3 hMPV182 G111C-E323C 10.37 12.67 3 Ns: number of independent IVE experiments. I. LISTING OF RAW SEQUENCES SEQ ID NO:8: Amino acid Sequence of the T4 Fibritin Foldon: GYIPEAPRDGQAYVRKDGEWVLLSTFL >hMPV178_DNA (SEQ ID NO:19) ATGAGCTGGAAAGTCATGATCATCATCAGCCTGCTGATCACCCCTCAGCACGGCCTGAA AGAGAGCTACCTGGAAGAAAGCTGCAGCACCATCACCGAGGGCTACCTGAGCGTGCTG AGAACCGGCTGGTACACCAACGTGTTCACCCTGGAAGTGGGCGACGTGGAAAACCTGA CCTGCACAGATGGCCCCAGCCTGATCAAGTGCGAGCTGGATCTGACAAAGAGCGCCCT GCGCGAGCTGAAAACCGTGTCTGCAGATCAGCTGGCCAGAGAGGAACAGATCGAGAA CCCCAGACAGAGCAGATTCGTGCTGGGAGCTATCGCCCTGGGAGTTGCTACAGCTGCT GCTGTGACAGCCGGAATCGCCATTGCCAAGACCATCCGGCTGGAAAGCGAAGTGAACG CCATCAAGGGCGCACTGAAAACCACCAACGAGGCCGTGTCTACCCTCGGCAACGGTGT TAGAGTGCTGGCCACAGCCGTGCGGGAACTGAAAGAATTCGTGTCCAAGAACCTGACC AGCGCCATCAACAAGAACAAGTGCGACATTGCCGACCTGAAGATGGCCGTGTCCTTCA GCTGCTTCAACCGGCGGTTCCTGAATGTCGTGCGGCAGTTCTCTGACAACGCCGGCAT CACACCAGCCATTAGCCTGGACCTGATGAACGACGCCGAACTGGCTAGAGCCGTGTCT TACATGCCTACCTCTGCCGGCCAGATCAAGCTGATGCTGGAAAACAGAGCCATGGTCC GACGGAAAGGCTTCGGCATCCTGATCGGCGTGTACGGCAGCAGCGTGATCTACATGGT GCAGCTGCCTATCTTCGGCGTGATCAACACCCCTTGCTGGATCATCAAGGCCGCTCCT AGCTGCAGCGAGAAGGACGGCAATTACGCCTGCCTGCTGAGAGAGGACCAAGGCTGG TACTGCAAGAATGCCGGCAGCACCGTGTACTACCCCAACGAGAAGGATTGCGAGACAC GGGGCGATCACGTGTTCTGTGATACAGCCGCCGGAATCAACGTGGCCGAGCAGAGCA GAGAGTGCAACATCAACATCAGCACCACAAACTACCCCTGCAAGGTGTCCACCGGCAG ACACCCTATCAGCATGGTGGCTCTGTCTCCACTGGGAGCCCTGGTGGCTTGTTATAAG GGCGTGTCCTGTAGCATCGGCAGCAATCAAGTGGGCATCATCAAGCAGCTGCCCAAGG GCTGCTCCTACATCACCAATCAGGACGCCGACACCGTGACCATCGACAATACCGTGTAT CAGCTGAGCAAGGTGGAAGGCGAACAGCACGTGATCAAGGGCAGACCTGTGTCCAAC AGCTTCGACCCCATCAGATTCCCCGAGGACCAGTTCAATGTGGCCCTGGACCAGGTGT TCGAGAGCATCGAGAATAGCCAGGCTCTGGTGGACCAGTCCAACAAGATCCTGAACTC CGCCGAGAAGGGCAACACCGGCTTCATCATCGTGATCATCCTGATTGCCGTGCTGGGC CTGACCATGATCAGCGTGTCCATCATCATTATCATCAAGAAAACGCGGAAGCCCGCCG GCGCCCCTCCAGAACTTAATGGCGTGACCAACGGCGGCTTCATTCCCCACTCT >hMPV178_mRNA (SEQ ID NO:20) AUGAGCUGGAAAGUCAUGAUCAUCAUCAGCCUGCUGAUCACCCCUCAGCACGGCCUG AAAGAGAGCUACCUGGAAGAAAGCUGCAGCACCAUCACCGAGGGCUACCUGAGCGUG CUGAGAACCGGCUGGUACACCAACGUGUUCACCCUGGAAGUGGGCGACGUGGAAAA CCUGACCUGCACAGAUGGCCCCAGCCUGAUCAAGUGCGAGCUGGAUCUGACAAAGA GCGCCCUGCGCGAGCUGAAAACCGUGUCUGCAGAUCAGCUGGCCAGAGAGGAACAG AUCGAGAACCCCAGACAGAGCAGAUUCGUGCUGGGAGCUAUCGCCCUGGGAGUUGC UACAGCUGCUGCUGUGACAGCCGGAAUCGCCAUUGCCAAGACCAUCCGGCUGGAAA GCGAAGUGAACGCCAUCAAGGGCGCACUGAAAACCACCAACGAGGCCGUGUCUACCC UCGGCAACGGUGUUAGAGUGCUGGCCACAGCCGUGCGGGAACUGAAAGAAUUCGUG UCCAAGAACCUGACCAGCGCCAUCAACAAGAACAAGUGCGACAUUGCCGACCUGAAG AUGGCCGUGUCCUUCAGCUGCUUCAACCGGCGGUUCCUGAAUGUCGUGCGGCAGUU CUCUGACAACGCCGGCAUCACACCAGCCAUUAGCCUGGACCUGAUGAACGACGCCGA ACUGGCUAGAGCCGUGUCUUACAUGCCUACCUCUGCCGGCCAGAUCAAGCUGAUGC UGGAAAACAGAGCCAUGGUCCGACGGAAAGGCUUCGGCAUCCUGAUCGGCGUGUAC GGCAGCAGCGUGAUCUACAUGGUGCAGCUGCCUAUCUUCGGCGUGAUCAACACCCC UUGCUGGAUCAUCAAGGCCGCUCCUAGCUGCAGCGAGAAGGACGGCAAUUACGCCU GCCUGCUGAGAGAGGACCAAGGCUGGUACUGCAAGAAUGCCGGCAGCACCGUGUAC UACCCCAACGAGAAGGAUUGCGAGACACGGGGCGAUCACGUGUUCUGUGAUACAGC CGCCGGAAUCAACGUGGCCGAGCAGAGCAGAGAGUGCAACAUCAACAUCAGCACCAC AAACUACCCCUGCAAGGUGUCCACCGGCAGACACCCUAUCAGCAUGGUGGCUCUGU CUCCACUGGGAGCCCUGGUGGCUUGUUAUAAGGGCGUGUCCUGUAGCAUCGGCAGC AAUCAAGUGGGCAUCAUCAAGCAGCUGCCCAAGGGCUGCUCCUACAUCACCAAUCAG GACGCCGACACCGUGACCAUCGACAAUACCGUGUAUCAGCUGAGCAAGGUGGAAGG CGAACAGCACGUGAUCAAGGGCAGACCUGUGUCCAACAGCUUCGACCCCAUCAGAUU CCCCGAGGACCAGUUCAAUGUGGCCCUGGACCAGGUGUUCGAGAGCAUCGAGAAUA GCCAGGCUCUGGUGGACCAGUCCAACAAGAUCCUGAACUCCGCCGAGAAGGGCAAC ACCGGCUUCAUCAUCGUGAUCAUCCUGAUUGCCGUGCUGGGCCUGACCAUGAUCAG CGUGUCCAUCAUCAUUAUCAUCAAGAAAACGCGGAAGCCCGCCGGCGCCCCUCCAGA ACUUAAUGGCGUGACCAACGGCGGCUUCAUUCCCCACUCU >hMPV179_DNA (SEQ ID NO:21) ATGAGCTGGAAAGTCATGATCATCATCAGCCTGCTGATCACCCCTCAGCACGGCCTGAA AGAGAGCTACCTGGAAGAAAGCTGCAGCACCATCACCGAGGGCTACCTGAGCGTGCTG AGAACCGGCTGGTACACCAACGTGTTCACCCTGGAAGTGGGCGACGTGGAAAACCTGA CCTGCACAGATGGCCCCAGCCTGATCAAGACCGAGCTGGATCTGACAAAGAGCGCCCT GCGCTGCCTGAAAACCGTGTCTGCAGATCAGCTGGCCAGAGAGGAACAGATCGAGAAC CCCAGACAGAGCAGATTCGTGCTGGGAGCTATCGCCCTGGGAGTTGCTACAGCTGCTG CTGTGACAGCCGGAATCGCCATTGCCAAGACCATCCGGCTGGAAAGCGAAGTGAACGC CATCAAGGGCGCACTGAAAACCACCAACGAGGCCGTGTCTACCCTCGGCAACGGTGTT AGAGTGCTGGCCACAGCCGTGCGGGAACTGAAAGAATTCGTGTCCAAGAACCTGACCA GCGCCATCAACAAGAACAAGTGCGACATTGCCGACCTGAAGATGGCCGTGTCCTTCAG CCAGTTCAACCGGCGGTTCCTGAATGTCGTGCGGCAGTTCTCTGACAACGCCGGCATC ACACCAGCCATTAGCCTGGACCTGATGAACTGCGCCGAACTGGCTAGAGCCGTGTCTT ACATGCCTACCTCTGCCGGCCAGATCAAGCTGATGCTGGAAAACAGAGCCATGGTCCG ACGGAAAGGCTTCGGCATCCTGATCGGCGTGTACGGCAGCAGCGTGATCTACATGGTG CAGCTGCCTATCTTCGGCGTGATCAACACCCCTTGCTGGATCATCAAGGCCGCTCCTA GCTGCAGCGAGAAGGACGGCAATTACGCCTGCCTGCTGAGAGAGGACCAAGGCTGGT ACTGCAAGAATGCCGGCAGCACCGTGTACTACCCCAACGAGAAGGATTGCGAGACACG GGGCGATCACGTGTTCTGTGATACAGCCGCCGGAATCAACGTGGCCGAGCAGAGCAG AGAGTGCAACATCAACATCAGCACCACAAACTACCCCTGCAAGGTGTCCACCGGCAGA CACCCTATCAGCATGGTGGCTCTGTCTCCACTGGGAGCCCTGGTGGCTTGTTATAAGG GCGTGTCCTGTAGCATCGGCAGCAATCAAGTGGGCATCATCAAGCAGCTGCCCAAGGG CTGCTCCTACATCACCAATCAGGACGCCGACACCGTGACCATCGACAATACCGTGTATC AGCTGAGCAAGGTGGAAGGCGAACAGCACGTGATCAAGGGCAGACCTGTGTCCAACA GCTTCGACCCCATCAGATTCCCCGAGGACCAGTTCAATGTGGCCCTGGACCAGGTGTT CGAGAGCATCGAGAATAGCCAGGCTCTGGTGGACCAGTCCAACAAGATCCTGAACTCC GCCGAGAAGGGCAACACCGGCTTCATCATCGTGATCATCCTGATTGCCGTGCTGGGCC TGACCATGATCAGCGTGTCCATCATCATTATCATCAAGAAAACGCGGAAGCCCGCCGG CGCCCCTCCAGAACTTAATGGCGTGACCAACGGCGGCTTCATTCCCCACTCT >hMPV179_mRNA (SEQ ID NO:22) AUGAGCUGGAAAGUCAUGAUCAUCAUCAGCCUGCUGAUCACCCCUCAGCACGGCCUG AAAGAGAGCUACCUGGAAGAAAGCUGCAGCACCAUCACCGAGGGCUACCUGAGCGUG CUGAGAACCGGCUGGUACACCAACGUGUUCACCCUGGAAGUGGGCGACGUGGAAAA CCUGACCUGCACAGAUGGCCCCAGCCUGAUCAAGACCGAGCUGGAUCUGACAAAGAG CGCCCUGCGCUGCCUGAAAACCGUGUCUGCAGAUCAGCUGGCCAGAGAGGAACAGA UCGAGAACCCCAGACAGAGCAGAUUCGUGCUGGGAGCUAUCGCCCUGGGAGUUGCU ACAGCUGCUGCUGUGACAGCCGGAAUCGCCAUUGCCAAGACCAUCCGGCUGGAAAG CGAAGUGAACGCCAUCAAGGGCGCACUGAAAACCACCAACGAGGCCGUGUCUACCCU CGGCAACGGUGUUAGAGUGCUGGCCACAGCCGUGCGGGAACUGAAAGAAUUCGUGU CCAAGAACCUGACCAGCGCCAUCAACAAGAACAAGUGCGACAUUGCCGACCUGAAGA UGGCCGUGUCCUUCAGCCAGUUCAACCGGCGGUUCCUGAAUGUCGUGCGGCAGUUC UCUGACAACGCCGGCAUCACACCAGCCAUUAGCCUGGACCUGAUGAACUGCGCCGAA CUGGCUAGAGCCGUGUCUUACAUGCCUACCUCUGCCGGCCAGAUCAAGCUGAUGCU GGAAAACAGAGCCAUGGUCCGACGGAAAGGCUUCGGCAUCCUGAUCGGCGUGUACG GCAGCAGCGUGAUCUACAUGGUGCAGCUGCCUAUCUUCGGCGUGAUCAACACCCCU UGCUGGAUCAUCAAGGCCGCUCCUAGCUGCAGCGAGAAGGACGGCAAUUACGCCUG CCUGCUGAGAGAGGACCAAGGCUGGUACUGCAAGAAUGCCGGCAGCACCGUGUACU ACCCCAACGAGAAGGAUUGCGAGACACGGGGCGAUCACGUGUUCUGUGAUACAGCC GCCGGAAUCAACGUGGCCGAGCAGAGCAGAGAGUGCAACAUCAACAUCAGCACCACA AACUACCCCUGCAAGGUGUCCACCGGCAGACACCCUAUCAGCAUGGUGGCUCUGUC UCCACUGGGAGCCCUGGUGGCUUGUUAUAAGGGCGUGUCCUGUAGCAUCGGCAGCA AUCAAGUGGGCAUCAUCAAGCAGCUGCCCAAGGGCUGCUCCUACAUCACCAAUCAGG ACGCCGACACCGUGACCAUCGACAAUACCGUGUAUCAGCUGAGCAAGGUGGAAGGC GAACAGCACGUGAUCAAGGGCAGACCUGUGUCCAACAGCUUCGACCCCAUCAGAUUC CCCGAGGACCAGUUCAAUGUGGCCCUGGACCAGGUGUUCGAGAGCAUCGAGAAUAG CCAGGCUCUGGUGGACCAGUCCAACAAGAUCCUGAACUCCGCCGAGAAGGGCAACAC CGGCUUCAUCAUCGUGAUCAUCCUGAUUGCCGUGCUGGGCCUGACCAUGAUCAGCG UGUCCAUCAUCAUUAUCAUCAAGAAAACGCGGAAGCCCGCCGGCGCCCCUCCAGAAC UUAAUGGCGUGACCAACGGCGGCUUCAUUCCCCACUCU >hMPV180_DNA (SEQ ID NO:23) ATGAGCTGGAAAGTCATGATCATCATCAGCCTGCTGATCACCCCTCAGCACGGCCTGAA AGAGAGCTACCTGGAAGAAAGCTGCAGCACCATCACCGAGGGCTACCTGAGCGTGCTG AGAACCGGCTGGTACACCAACGTGTTCACCCTGGAAGTGGGCGACGTGGAAAACCTGA CCTGCACAGATGGCCCCAGCCTGATCAAGACCGAGCTGGATCTGACAAAGAGCGCCCT GCGCGAGCTGAAAACCGTGTCTGCAGATCAGCTGGCCAGAGAGGAACAGATCGAGAA CCCCAGACAGAGCAGATTCGTGCTGGGAGCTATCGCCCTGGGAGTTGCTACAGCTGCT GCTGTGACAGCCGGAATCGCCATTGCCAAGACCATCCGGCTGGAAAGCGAAGTGAACG CCATCAAGGGCGCACTGAAAACCACCAACGAGGCCGTGTCTACCCTCGGCAACGGTGT TAGAGTGCTGGCCACAGCCGTGCGGGAACTGAAAGAATTCGTGTCCAAGAACCTGACC AGCGCCATCAACAAGAACAAGTGCGACATTGCCGACCTGAAGATGGCCGTGTCCTTCA GCCAGTTCAACCGGCGGTTCCTGAATGTCGTGCGGCAGTTCTCTGACAACTGCGGCAT CACACCAGCCATTAGCCTGGACCTGATGAACGACGCCGAACTGGCTAGAGCCGTGTCT TACATGCCTACCTCTGCCGGCCAGATCAAGCTGATGCTGGAAAACAGAGCCTGCGTCC GACGGAAAGGCTTCGGCATCCTGATCGGCGTGTACGGCAGCAGCGTGATCTACATGGT GCAGCTGCCTATCTTCGGCGTGATCAACACCCCTTGCTGGATCATCAAGGCCGCTCCT AGCTGCAGCGAGAAGGACGGCAATTACGCCTGCCTGCTGAGAGAGGACCAAGGCTGG TACTGCAAGAATGCCGGCAGCACCGTGTACTACCCCAACGAGAAGGATTGCGAGACAC GGGGCGATCACGTGTTCTGTGATACAGCCGCCGGAATCAACGTGGCCGAGCAGAGCA GAGAGTGCAACATCAACATCAGCACCACAAACTACCCCTGCAAGGTGTCCACCGGCAG ACACCCTATCAGCATGGTGGCTCTGTCTCCACTGGGAGCCCTGGTGGCTTGTTATAAG GGCGTGTCCTGTAGCATCGGCAGCAATCAAGTGGGCATCATCAAGCAGCTGCCCAAGG GCTGCTCCTACATCACCAATCAGGACGCCGACACCGTGACCATCGACAATACCGTGTAT CAGCTGAGCAAGGTGGAAGGCGAACAGCACGTGATCAAGGGCAGACCTGTGTCCAAC AGCTTCGACCCCATCAGATTCCCCGAGGACCAGTTCAATGTGGCCCTGGACCAGGTGT TCGAGAGCATCGAGAATAGCCAGGCTCTGGTGGACCAGTCCAACAAGATCCTGAACTC CGCCGAGAAGGGCAACACCGGCTTCATCATCGTGATCATCCTGATTGCCGTGCTGGGC CTGACCATGATCAGCGTGTCCATCATCATTATCATCAAGAAAACGCGGAAGCCCGCCG GCGCCCCTCCAGAACTTAATGGCGTGACCAACGGCGGCTTCATTCCCCACTCT >hMPV180_mRNA (SEQ ID NO:24) AUGAGCUGGAAAGUCAUGAUCAUCAUCAGCCUGCUGAUCACCCCUCAGCACGGCCUG AAAGAGAGCUACCUGGAAGAAAGCUGCAGCACCAUCACCGAGGGCUACCUGAGCGUG CUGAGAACCGGCUGGUACACCAACGUGUUCACCCUGGAAGUGGGCGACGUGGAAAA CCUGACCUGCACAGAUGGCCCCAGCCUGAUCAAGACCGAGCUGGAUCUGACAAAGAG CGCCCUGCGCGAGCUGAAAACCGUGUCUGCAGAUCAGCUGGCCAGAGAGGAACAGA UCGAGAACCCCAGACAGAGCAGAUUCGUGCUGGGAGCUAUCGCCCUGGGAGUUGCU ACAGCUGCUGCUGUGACAGCCGGAAUCGCCAUUGCCAAGACCAUCCGGCUGGAAAG CGAAGUGAACGCCAUCAAGGGCGCACUGAAAACCACCAACGAGGCCGUGUCUACCCU CGGCAACGGUGUUAGAGUGCUGGCCACAGCCGUGCGGGAACUGAAAGAAUUCGUGU CCAAGAACCUGACCAGCGCCAUCAACAAGAACAAGUGCGACAUUGCCGACCUGAAGA UGGCCGUGUCCUUCAGCCAGUUCAACCGGCGGUUCCUGAAUGUCGUGCGGCAGUUC UCUGACAACUGCGGCAUCACACCAGCCAUUAGCCUGGACCUGAUGAACGACGCCGAA CUGGCUAGAGCCGUGUCUUACAUGCCUACCUCUGCCGGCCAGAUCAAGCUGAUGCU GGAAAACAGAGCCUGCGUCCGACGGAAAGGCUUCGGCAUCCUGAUCGGCGUGUACG GCAGCAGCGUGAUCUACAUGGUGCAGCUGCCUAUCUUCGGCGUGAUCAACACCCCU UGCUGGAUCAUCAAGGCCGCUCCUAGCUGCAGCGAGAAGGACGGCAAUUACGCCUG CCUGCUGAGAGAGGACCAAGGCUGGUACUGCAAGAAUGCCGGCAGCACCGUGUACU ACCCCAACGAGAAGGAUUGCGAGACACGGGGCGAUCACGUGUUCUGUGAUACAGCC GCCGGAAUCAACGUGGCCGAGCAGAGCAGAGAGUGCAACAUCAACAUCAGCACCACA AACUACCCCUGCAAGGUGUCCACCGGCAGACACCCUAUCAGCAUGGUGGCUCUGUC UCCACUGGGAGCCCUGGUGGCUUGUUAUAAGGGCGUGUCCUGUAGCAUCGGCAGCA AUCAAGUGGGCAUCAUCAAGCAGCUGCCCAAGGGCUGCUCCUACAUCACCAAUCAGG ACGCCGACACCGUGACCAUCGACAAUACCGUGUAUCAGCUGAGCAAGGUGGAAGGC GAACAGCACGUGAUCAAGGGCAGACCUGUGUCCAACAGCUUCGACCCCAUCAGAUUC CCCGAGGACCAGUUCAAUGUGGCCCUGGACCAGGUGUUCGAGAGCAUCGAGAAUAG CCAGGCUCUGGUGGACCAGUCCAACAAGAUCCUGAACUCCGCCGAGAAGGGCAACAC CGGCUUCAUCAUCGUGAUCAUCCUGAUUGCCGUGCUGGGCCUGACCAUGAUCAGCG UGUCCAUCAUCAUUAUCAUCAAGAAAACGCGGAAGCCCGCCGGCGCCCCUCCAGAAC UUAAUGGCGUGACCAACGGCGGCUUCAUUCCCCACUCU >hMPV181_DNA (SEQ ID NO:25) ATGAGCTGGAAAGTCATGATCATCATCAGCCTGCTGATCACCCCTCAGCACGGCCTGAA AGAGAGCTACCTGGAAGAAAGCTGCAGCACCATCACCGAGGGCTACCTGAGCGTGCTG AGAACCGGCTGGTACACCAACGTGTTCACCCTGGAAGTGGGCGACGTGGAAAACCTGA CCTGCACAGATGGCCCCAGCCTGATCAAGACCGAGCTGGATCTGACAAAGAGCGCCCT GCGCGAGCTGAAAACCGTGTCTGCAGATCAGCTGGCCAGAGAGGAACAGATCGAGAA CCCCAGACAGAGCAGATTCGTGCTGGGAGCTATCGCCCTGGGAGTTGCTACAGCTGCT GCTGTGACAGCCGGAATCGCCATTGCCAAGACCATCCGGCTGGAAAGCGAAGTGAACG CCATCAAGGGCGCACTGAAAACCACCAACGAGGCCGTGTCTACCCTCGGCAACGGTGT TAGAGTGCTGGCCACAGCCGTGCGGGAACTGAAAGAATTCGTGTCCAAGAACCTGACC AGCGCCATCAACAAGAACAAGTGCGACATTGCCGACCTGAAGATGGCCGTGTCCTTCA GCCAGTTCAACCGGCGGTTCCTGAATGTCGTGCGGCAGTTCTCTGACAACGCCGGCAT CACACCAGCCATTAGCCTGGACCTGATGAACGACGCCGAACTGGCTAGAGCCGTGTCT TACATGCCTACCTCTGCCGGCCAGATCAAGCTGATGCTGGAAAACAGAGCCATGGTCC GACGGAAAGGCTTCGGCATCCTGATCGGCGTGTACGGCAGCAGCGTGATCTACATGGT GCAGCTGCCTATCTTCGGCGTGATCAACACCCCTTGCTGGATCATCAAGGCCGCTCCT AGCTGCAGCGAGAAGGACGGCAATTACGCCTGCCTGCTGAGAGAGGACCAAGGCTGG TACTGCAAGAATGCCGGCAGCACCGTGTACTACCCCAACGAGAAGGATTGCGAGACAC GGGGCGATCACGTGTTCTGTGATTGCGCCGCCGGAATCAACGTGGCCGAGCAGAGCA GAGAGTGCAACATCAACATCAGCACCACAAACTACCCCTGCAAGGTGTCCACCGGCAG ACACCCTATCAGCATGGTGGCTCTGTCTCCACTGGGAGCCCTGGTGGCTTGTTATAAG GGCGTGTCCTGTAGCATCGGCAGCAATCAAGTGGGCATCATCAAGCAGCTGCCCAAGG GCTGCTCCTACATCACCAATCAGGACGCCGACACCGTGACCATCGACAATTGCGTGTAT CAGCTGAGCAAGGTGGAAGGCGAACAGCACGTGATCAAGGGCAGACCTGTGTCCAAC AGCTTCGACCCCATCAGATTCCCCGAGGACCAGTTCAATGTGGCCCTGGACCAGGTGT TCGAGAGCATCGAGAATAGCCAGGCTCTGGTGGACCAGTCCAACAAGATCCTGAACTC CGCCGAGAAGGGCAACACCGGCTTCATCATCGTGATCATCCTGATTGCCGTGCTGGGC CTGACCATGATCAGCGTGTCCATCATCATTATCATCAAGAAAACGCGGAAGCCCGCCG GCGCCCCTCCAGAACTTAATGGCGTGACCAACGGCGGCTTCATTCCCCACTCT >hMPV181_mRNA (SEQ ID NO:26) AUGAGCUGGAAAGUCAUGAUCAUCAUCAGCCUGCUGAUCACCCCUCAGCACGGCCUG AAAGAGAGCUACCUGGAAGAAAGCUGCAGCACCAUCACCGAGGGCUACCUGAGCGUG CUGAGAACCGGCUGGUACACCAACGUGUUCACCCUGGAAGUGGGCGACGUGGAAAA CCUGACCUGCACAGAUGGCCCCAGCCUGAUCAAGACCGAGCUGGAUCUGACAAAGAG CGCCCUGCGCGAGCUGAAAACCGUGUCUGCAGAUCAGCUGGCCAGAGAGGAACAGA UCGAGAACCCCAGACAGAGCAGAUUCGUGCUGGGAGCUAUCGCCCUGGGAGUUGCU ACAGCUGCUGCUGUGACAGCCGGAAUCGCCAUUGCCAAGACCAUCCGGCUGGAAAG CGAAGUGAACGCCAUCAAGGGCGCACUGAAAACCACCAACGAGGCCGUGUCUACCCU CGGCAACGGUGUUAGAGUGCUGGCCACAGCCGUGCGGGAACUGAAAGAAUUCGUGU CCAAGAACCUGACCAGCGCCAUCAACAAGAACAAGUGCGACAUUGCCGACCUGAAGA UGGCCGUGUCCUUCAGCCAGUUCAACCGGCGGUUCCUGAAUGUCGUGCGGCAGUUC UCUGACAACGCCGGCAUCACACCAGCCAUUAGCCUGGACCUGAUGAACGACGCCGAA CUGGCUAGAGCCGUGUCUUACAUGCCUACCUCUGCCGGCCAGAUCAAGCUGAUGCU GGAAAACAGAGCCAUGGUCCGACGGAAAGGCUUCGGCAUCCUGAUCGGCGUGUACG GCAGCAGCGUGAUCUACAUGGUGCAGCUGCCUAUCUUCGGCGUGAUCAACACCCCU UGCUGGAUCAUCAAGGCCGCUCCUAGCUGCAGCGAGAAGGACGGCAAUUACGCCUG CCUGCUGAGAGAGGACCAAGGCUGGUACUGCAAGAAUGCCGGCAGCACCGUGUACU ACCCCAACGAGAAGGAUUGCGAGACACGGGGCGAUCACGUGUUCUGUGAUUGCGCC GCCGGAAUCAACGUGGCCGAGCAGAGCAGAGAGUGCAACAUCAACAUCAGCACCACA AACUACCCCUGCAAGGUGUCCACCGGCAGACACCCUAUCAGCAUGGUGGCUCUGUC UCCACUGGGAGCCCUGGUGGCUUGUUAUAAGGGCGUGUCCUGUAGCAUCGGCAGCA AUCAAGUGGGCAUCAUCAAGCAGCUGCCCAAGGGCUGCUCCUACAUCACCAAUCAGG ACGCCGACACCGUGACCAUCGACAAUUGCGUGUAUCAGCUGAGCAAGGUGGAAGGC GAACAGCACGUGAUCAAGGGCAGACCUGUGUCCAACAGCUUCGACCCCAUCAGAUUC CCCGAGGACCAGUUCAAUGUGGCCCUGGACCAGGUGUUCGAGAGCAUCGAGAAUAG CCAGGCUCUGGUGGACCAGUCCAACAAGAUCCUGAACUCCGCCGAGAAGGGCAACAC CGGCUUCAUCAUCGUGAUCAUCCUGAUUGCCGUGCUGGGCCUGACCAUGAUCAGCG UGUCCAUCAUCAUUAUCAUCAAGAAAACGCGGAAGCCCGCCGGCGCCCCUCCAGAAC UUAAUGGCGUGACCAACGGCGGCUUCAUUCCCCACUCU >hMPV182_DNA (SEQ ID NO:27) ATGAGCTGGAAAGTCATGATCATCATCAGCCTGCTGATCACCCCTCAGCACGGCCTGAA AGAGAGCTACCTGGAAGAAAGCTGCAGCACCATCACCGAGGGCTACCTGAGCGTGCTG AGAACCGGCTGGTACACCAACGTGTTCACCCTGGAAGTGGGCGACGTGGAAAACCTGA CCTGCACAGATGGCCCCAGCCTGATCAAGACCGAGCTGGATCTGACAAAGAGCGCCCT GCGCGAGCTGAAAACCGTGTCTGCAGATCAGCTGGCCAGAGAGGAACAGATCGAGAA CCCCAGACAGAGCAGATTCGTGCTGGGAGCTATCGCCCTGTGCGTTGCTACAGCTGCT GCTGTGACAGCCGGAATCGCCATTGCCAAGACCATCCGGCTGGAAAGCGAAGTGAACG CCATCAAGGGCGCACTGAAAACCACCAACGAGGCCGTGTCTACCCTCGGCAACGGTGT TAGAGTGCTGGCCACAGCCGTGCGGGAACTGAAAGAATTCGTGTCCAAGAACCTGACC AGCGCCATCAACAAGAACAAGTGCGACATTGCCGACCTGAAGATGGCCGTGTCCTTCA GCCAGTTCAACCGGCGGTTCCTGAATGTCGTGCGGCAGTTCTCTGACAACGCCGGCAT CACACCAGCCATTAGCCTGGACCTGATGAACGACGCCGAACTGGCTAGAGCCGTGTCT TACATGCCTACCTCTGCCGGCCAGATCAAGCTGATGCTGGAAAACAGAGCCATGGTCC GACGGAAAGGCTTCGGCATCCTGATCGGCGTGTACGGCAGCAGCGTGATCTACATGGT GCAGCTGCCTATCTTCGGCGTGATCAACACCCCTTGCTGGATCATCAAGGCCGCTCCT AGCTGCAGCGAGAAGGACGGCAATTACGCCTGCCTGCTGAGAGAGGACCAAGGCTGG TACTGCAAGAATGCCGGCAGCACCGTGTACTACCCCAACTGCAAGGATTGCGAGACAC GGGGCGATCACGTGTTCTGTGATACAGCCGCCGGAATCAACGTGGCCGAGCAGAGCA GAGAGTGCAACATCAACATCAGCACCACAAACTACCCCTGCAAGGTGTCCACCGGCAG ACACCCTATCAGCATGGTGGCTCTGTCTCCACTGGGAGCCCTGGTGGCTTGTTATAAG GGCGTGTCCTGTAGCATCGGCAGCAATCAAGTGGGCATCATCAAGCAGCTGCCCAAGG GCTGCTCCTACATCACCAATCAGGACGCCGACACCGTGACCATCGACAATACCGTGTAT CAGCTGAGCAAGGTGGAAGGCGAACAGCACGTGATCAAGGGCAGACCTGTGTCCAAC AGCTTCGACCCCATCAGATTCCCCGAGGACCAGTTCAATGTGGCCCTGGACCAGGTGT TCGAGAGCATCGAGAATAGCCAGGCTCTGGTGGACCAGTCCAACAAGATCCTGAACTC CGCCGAGAAGGGCAACACCGGCTTCATCATCGTGATCATCCTGATTGCCGTGCTGGGC CTGACCATGATCAGCGTGTCCATCATCATTATCATCAAGAAAACGCGGAAGCCCGCCG GCGCCCCTCCAGAACTTAATGGCGTGACCAACGGCGGCTTCATTCCCCACTCT >hMPV182_mRNA (SEQ ID NO:28) AUGAGCUGGAAAGUCAUGAUCAUCAUCAGCCUGCUGAUCACCCCUCAGCACGGCCUG AAAGAGAGCUACCUGGAAGAAAGCUGCAGCACCAUCACCGAGGGCUACCUGAGCGUG CUGAGAACCGGCUGGUACACCAACGUGUUCACCCUGGAAGUGGGCGACGUGGAAAA CCUGACCUGCACAGAUGGCCCCAGCCUGAUCAAGACCGAGCUGGAUCUGACAAAGAG CGCCCUGCGCGAGCUGAAAACCGUGUCUGCAGAUCAGCUGGCCAGAGAGGAACAGA UCGAGAACCCCAGACAGAGCAGAUUCGUGCUGGGAGCUAUCGCCCUGUGCGUUGCU ACAGCUGCUGCUGUGACAGCCGGAAUCGCCAUUGCCAAGACCAUCCGGCUGGAAAG CGAAGUGAACGCCAUCAAGGGCGCACUGAAAACCACCAACGAGGCCGUGUCUACCCU CGGCAACGGUGUUAGAGUGCUGGCCACAGCCGUGCGGGAACUGAAAGAAUUCGUGU CCAAGAACCUGACCAGCGCCAUCAACAAGAACAAGUGCGACAUUGCCGACCUGAAGA UGGCCGUGUCCUUCAGCCAGUUCAACCGGCGGUUCCUGAAUGUCGUGCGGCAGUUC UCUGACAACGCCGGCAUCACACCAGCCAUUAGCCUGGACCUGAUGAACGACGCCGAA CUGGCUAGAGCCGUGUCUUACAUGCCUACCUCUGCCGGCCAGAUCAAGCUGAUGCU GGAAAACAGAGCCAUGGUCCGACGGAAAGGCUUCGGCAUCCUGAUCGGCGUGUACG GCAGCAGCGUGAUCUACAUGGUGCAGCUGCCUAUCUUCGGCGUGAUCAACACCCCU UGCUGGAUCAUCAAGGCCGCUCCUAGCUGCAGCGAGAAGGACGGCAAUUACGCCUG CCUGCUGAGAGAGGACCAAGGCUGGUACUGCAAGAAUGCCGGCAGCACCGUGUACU ACCCCAACUGCAAGGAUUGCGAGACACGGGGCGAUCACGUGUUCUGUGAUACAGCC GCCGGAAUCAACGUGGCCGAGCAGAGCAGAGAGUGCAACAUCAACAUCAGCACCACA AACUACCCCUGCAAGGUGUCCACCGGCAGACACCCUAUCAGCAUGGUGGCUCUGUC UCCACUGGGAGCCCUGGUGGCUUGUUAUAAGGGCGUGUCCUGUAGCAUCGGCAGCA AUCAAGUGGGCAUCAUCAAGCAGCUGCCCAAGGGCUGCUCCUACAUCACCAAUCAGG ACGCCGACACCGUGACCAUCGACAAUACCGUGUAUCAGCUGAGCAAGGUGGAAGGC GAACAGCACGUGAUCAAGGGCAGACCUGUGUCCAACAGCUUCGACCCCAUCAGAUUC CCCGAGGACCAGUUCAAUGUGGCCCUGGACCAGGUGUUCGAGAGCAUCGAGAAUAG CCAGGCUCUGGUGGACCAGUCCAACAAGAUCCUGAACUCCGCCGAGAAGGGCAACAC CGGCUUCAUCAUCGUGAUCAUCCUGAUUGCCGUGCUGGGCCUGACCAUGAUCAGCG UGUCCAUCAUCAUUAUCAUCAAGAAAACGCGGAAGCCCGCCGGCGCCCCUCCAGAAC UUAAUGGCGUGACCAACGGCGGCUUCAUUCCCCACUCU SAIG SEQ ID NO: 32 – hMPV B precursor polypeptide (ectodomain with foldon and tags) MSWKVMIIISLLITPQHGLKESYLEESCSTITEGYLSVLRTGWYTNVFTLEVGDVENLTCTDG PSLIKTELDLTKSALRELKTVSADQLAREEQIENPRQSRFVLGAIALGVATAAAVTAGIAIAK TIRLESEVNAIKGALKTTNEAVSTLGNGVRVLATAVRELKEFVSKNLTSAINKNKCDIADLKMA VSFSQFNRRFLNVVRQFSDNAGITPAISLDLMNDAELARAVSYMPTSAGQIKLMLENRAMV RRKGFGILIGVYGSSVIYMVQLPIFGVINTPCWIIKAAPSCSEKDGNYACLLREDQGWYCKNA GSTVYYPNEKDCETRGDHVFCDTAAGINVAEQSRECNINISTTNYPCKVSTGRHPISMVALS PLGALVACYKGVSCSIGSNQVGIIKQLPKGCSYITNQDADTVTIDNTVYQLSKVEGEQHVIKG RPVSNSFDPIRFPEDQFNVALDQVFESIENSQALVDQSNKILNSAEKGNTGGGSGYIPEAPR Annotated sequence of the hMPV-B precursor polypeptide. Underlined sequence represents the signal peptide, bolded sequence represents F2 polypeptide, and underlined and bolded sequence represents the T4 fibritin foldon, PreScission cleavage site, Strep Tag II and linker sequences. SEQ ID NO:33: Amino Acid Sequence of Heavy Chain Variable Domain of Antibody MPE8 mAb: EVQLVESGGGLVKPGGSLRLSCAASGFTFSSYSMNWVRQAPGKGLEWVSSISASSSYSDY ADSAKGRFTISRDNAKTSLFLQMNSLRAEDTAIYFCARARATGYSSITPYFDIWGQGTLVTV SS SEQ ID NO:34: Amino Acid Sequence of Light Chain Variable Domain of Antibody MPE8 mAb: QSVVTQTPSVSGAPGQRVTISCTGSSSNIGAGYDVHWYQQLPGTAPKLLIYDNNNRPSGVP DRFSASKSGTSASLAITGLQAEDEADYYCQSYDRNLSGVFGTGTKVTVL SEQ ID NO:35: Amino Acid Sequence of Heavy Chain Variable Domain of Antibody hMPV-2 mAb: QVQLQQSGAEVKKPGASVKVSCKASGYTFTSYGISWVRQAPGQGLEWMGWISGYNGNTN YAQTFQGTFTMTTDTSTSTAYMELRRLRSGDTAVYYCARDRYYASGSYNGMDVWGQGTT VTVSS SEQ ID NO:36: Amino Acid Sequence of Light Chain Variable Domain of Antibody hMPV-2 mAb: QSALTQPPSASGAPGQRVTVSCSGSSSNVGSSSVYWYQQLPGTAPKLLIYRNNQRPSGVP DRFSGSKSGTSASLAISGLRSEDEADYYCAAWDDSLSGWVFGGGTKLTVL SEQ ID NO:37: F0 protein sequences from selected PIV1 strain (HPIV1/WI/629- D00712/2009 / AFP49460.1) MQSSEILLLVYSSLLLSSSLCQIPVDKLSNVGVIINEGKLLKIAGSYESRYIVLSLVPSIDLQDG CGTTQIIQYKNLLNRLLIPLKDALDLQESLITITNDTTVTNDNPQTRFFGAVIGTIALGVATAAQI TAGIALAEAREARKDIALIKDSIVKTHNSVEFIQRGIGEQIIALKTLQDFVNDEIRPAIGELRCET TALKLGIKLTQHYSELATAFSSNLGTIGEKSLTLQALSSLYSANITEILSTIKKDKSDIYDIIYTEQ VKGTVIDVDLEKYMVTLLVKIPILSEIPGVLIYRASSISYNIEGEEWHVAIPNYIINKASSLGGAD VTNCIESKLAYICPRDPTQLIPDNQQKCILGDVSKCPVTKVINNLVPKFAFINGGVVANCIAST CTCGTNRIPVNQDRSKGVTFLTYTNCGLIGINGIELYANKRGRDTTWGNQIIKVGPAVSIRPV INSTNNSPINAYTLESRMKNPYMGNHSN SEQ ID NO:38: F0 protein sequences from selected PIV3 strain (HPIV3/MEX/2545/2006 / AGT75285.1) MLISILLIITTMIMASHCQIDITKLQHVGVLVNSPKGMKISQNFETRYLILSLIPKIEDSNSCGDQ QIKQYKRLLDRLIIPLYDGLRLQKDVIVTNQESNENTDPRTERFFGGVIGTIALGVATSAQITA AVALVEAKQARSDIEKLKEAIRDTNKAVQSVQSSVGNLIVAIKSVQDYVNKEIVPSIARLGCEA AGLQLGIALTQHYSELTNIFGDNIGSLQEKGIKLQGIASLYRTNITEIFTTSTVDKYDIYDLLFTE SIKVRVIDVDLNDYSITLQVRLPLLTRLLNTQIYKVDSISYNIQNREWYIPLPSHIMTKGAFLGG ADVKECIEAFSSYICPSDPGFVLNHEMESCLSGNISQCPRTTVTSDIVPRYAFVNGGVVANCI TTTCTCNGIGNRINQPPDQGVKIITHKECNTIGINGMLFNTNKEGTLAFYTPDDITLNNSVALD PIDISIELNKAKSDLEESKEWIRRSNQKLDSIGSWHQSSTTIIVILIMMIILFIINITIITIAIKYYRIQK RNRVDQNDKPYVLTNK >hMPV B WT_DNA (SEQ ID NO:39) ATGAGCTGGAAAGTCATGATCATCATCAGCCTGCTGATCACCCCTCAGCACGGC CTGAAAGAGAGCTACCTGGAAGAAAGCTGCAGCACCATCACCGAGGGCTACCT GAGCGTGCTGAGAACCGGCTGGTACACCAACGTGTTCACCCTGGAAGTGGGC GACGTGGAAAACCTGACCTGCACAGATGGCCCCAGCCTGATCAAGACCGAGCT GGATCTGACAAAGAGCGCCCTGCGCGAGCTGAAAACCGTGTCTGCAGATCAGC TGGCCAGAGAGGAACAGATCGAGAACCCCAGACAGAGCAGATTCGTGCTGGGA GCTATCGCCCTGGGAGTTGCTACAGCTGCTGCTGTGACAGCCGGAATCGCCAT TGCCAAGACCATCCGGCTGGAAAGCGAAGTGAACGCCATCAAGGGCGCACTGA AAACCACCAACGAGGCCGTGTCTACCCTCGGCAACGGTGTTAGAGTGCTGGCC ACAGCCGTGCGGGAACTGAAAGAATTCGTGTCCAAGAACCTGACCAGCGCCAT CAACAAGAACAAGTGCGACATTGCCGACCTGAAGATGGCCGTGTCCTTCAGCC AGTTCAACCGGCGGTTCCTGAATGTCGTGCGGCAGTTCTCTGACAACGCCGGC ATCACACCAGCCATTAGCCTGGACCTGATGAACGACGCCGAACTGGCTAGAGC CGTGTCTTACATGCCTACCTCTGCCGGCCAGATCAAGCTGATGCTGGAAAACAG AGCCATGGTCCGACGGAAAGGCTTCGGCATCCTGATCGGCGTGTACGGCAGCA GCGTGATCTACATGGTGCAGCTGCCTATCTTCGGCGTGATCAACACCCCTTGCT GGATCATCAAGGCCGCTCCTAGCTGCAGCGAGAAGGACGGCAATTACGCCTGC CTGCTGAGAGAGGACCAAGGCTGGTACTGCAAGAATGCCGGCAGCACCGTGTA CTACCCCAACGAGAAGGATTGCGAGACACGGGGCGATCACGTGTTCTGTGATA CAGCCGCCGGAATCAACGTGGCCGAGCAGAGCAGAGAGTGCAACATCAACATC AGCACCACAAACTACCCCTGCAAGGTGTCCACCGGCAGACACCCTATCAGCAT GGTGGCTCTGTCTCCACTGGGAGCCCTGGTGGCTTGTTATAAGGGCGTGTCCT GTAGCATCGGCAGCAATCAAGTGGGCATCATCAAGCAGCTGCCCAAGGGCTGC TCCTACATCACCAATCAGGACGCCGACACCGTGACCATCGACAATACCGTGTAT CAGCTGAGCAAGGTGGAAGGCGAACAGCACGTGATCAAGGGCAGACCTGTGT CCAACAGCTTCGACCCCATCAGATTCCCCGAGGACCAGTTCAATGTGGCCCTG GACCAGGTGTTCGAGAGCATCGAGAATAGCCAGGCTCTGGTGGACCAGTCCAA CAAGATCCTGAACTCCGCCGAGAAGGGCAACACCGGCTTCATCATCGTGATCA TCCTGATTGCCGTGCTGGGCCTGACCATGATCAGCGTGTCCATCATCATTATCA TCAAGAAAACGCGGAAGCCCGCCGGCGCCCCTCCAGAACTTAATGGCGTGACC AACGGCGGCTTCATTCCCCACTCT >hMPV B WT_mRNA (SEQ ID NO:40) AUGAGCUGGAAAGUCAUGAUCAUCAUCAGCCUGCUGAUCACCCCUCAGCACG GCCUGAAAGAGAGCUACCUGGAAGAAAGCUGCAGCACCAUCACCGAGGGCUA CCUGAGCGUGCUGAGAACCGGCUGGUACACCAACGUGUUCACCCUGGAAGU GGGCGACGUGGAAAACCUGACCUGCACAGAUGGCCCCAGCCUGAUCAAGACC GAGCUGGAUCUGACAAAGAGCGCCCUGCGCGAGCUGAAAACCGUGUCUGCA GAUCAGCUGGCCAGAGAGGAACAGAUCGAGAACCCCAGACAGAGCAGAUUCG UGCUGGGAGCUAUCGCCCUGGGAGUUGCUACAGCUGCUGCUGUGACAGCCG GAAUCGCCAUUGCCAAGACCAUCCGGCUGGAAAGCGAAGUGAACGCCAUCAA GGGCGCACUGAAAACCACCAACGAGGCCGUGUCUACCCUCGGCAACGGUGU UAGAGUGCUGGCCACAGCCGUGCGGGAACUGAAAGAAUUCGUGUCCAAGAAC CUGACCAGCGCCAUCAACAAGAACAAGUGCGACAUUGCCGACCUGAAGAUGG CCGUGUCCUUCAGCCAGUUCAACCGGCGGUUCCUGAAUGUCGUGCGGCAGU UCUCUGACAACGCCGGCAUCACACCAGCCAUUAGCCUGGACCUGAUGAACGA CGCCGAACUGGCUAGAGCCGUGUCUUACAUGCCUACCUCUGCCGGCCAGAU CAAGCUGAUGCUGGAAAACAGAGCCAUGGUCCGACGGAAAGGCUUCGGCAUC CUGAUCGGCGUGUACGGCAGCAGCGUGAUCUACAUGGUGCAGCUGCCUAUC UUCGGCGUGAUCAACACCCCUUGCUGGAUCAUCAAGGCCGCUCCUAGCUGCA GCGAGAAGGACGGCAAUUACGCCUGCCUGCUGAGAGAGGACCAAGGCUGGU ACUGCAAGAAUGCCGGCAGCACCGUGUACUACCCCAACGAGAAGGAUUGCGA GACACGGGGCGAUCACGUGUUCUGUGAUACAGCCGCCGGAAUCAACGUGGC CGAGCAGAGCAGAGAGUGCAACAUCAACAUCAGCACCACAAACUACCCCUGC AAGGUGUCCACCGGCAGACACCCUAUCAGCAUGGUGGCUCUGUCUCCACUG GGAGCCCUGGUGGCUUGUUAUAAGGGCGUGUCCUGUAGCAUCGGCAGCAAU CAAGUGGGCAUCAUCAAGCAGCUGCCCAAGGGCUGCUCCUACAUCACCAAUC AGGACGCCGACACCGUGACCAUCGACAAUACCGUGUAUCAGCUGAGCAAGGU GGAAGGCGAACAGCACGUGAUCAAGGGCAGACCUGUGUCCAACAGCUUCGAC CCCAUCAGAUUCCCCGAGGACCAGUUCAAUGUGGCCCUGGACCAGGUGUUC GAGAGCAUCGAGAAUAGCCAGGCUCUGGUGGACCAGUCCAACAAGAUCCUGA ACUCCGCCGAGAAGGGCAACACCGGCUUCAUCAUCGUGAUCAUCCUGAUUGC CGUGCUGGGCCUGACCAUGAUCAGCGUGUCCAUCAUCAUUAUCAUCAAGAAA ACGCGGAAGCCCGCCGGCGCCCCUCCAGAACUUAAUGGCGUGACCAACGGC GGCUUCAUUCCCCACUCU

Claims

CLAIMS 1. A mutant of a wild-type hMPV F protein, which mutant comprises a F1 polypeptide and a F2 polypeptide, wherein the mutant comprises at least one amino acid mutation relative to the amino acid sequence of the wild-type hMPV F protein, and wherein the amino acid mutation is an engineered interprotomer disulfide mutation selected from the group consisting of (1) 69C and 195C; (2) 80C and 224C; (3) 211C and 250C; (4) 337C and 423C; and, (5) 111C and 323C.

2. The mutant according to claim 1 wherein the engineered interprotomer disulfide mutation is selected from the group consisting of (1) T69C and Q195C; (2) E80C and D224C; (3) A211C and M250C; (4) T337C and T423C; and, (5) G111C and E323C.

3. The mutant according to claim 1 or 2 wherein the mutant comprises engineered interprotomer disulfide mutations selected from the group consisting of: (1) T69C and Q195C; (2) E80C and D224C; (3) A211C and M250C; (4) T337C and T423C, (5) G111C and E323C; (6) T69C, Q195C, E80C and D224C; (7) T69C, Q195C, A211C and M250C; (8) T69C, Q195C, T337C and T423C; (9) T69C, Q195C, G111C and E323C; (10) E80C, D224C, A211C and M250C; (11) E80C, D224C, T337C and T423C; (12) E80C, D224C, G111C and E323C; (13) A211C, M250C, T337C and T423C; (14) A211C, M250C, G111C and E323C; (15) T337C, T423C, G111C and E323C; (16) T69C, Q195C, E80C, D224C, A211C and M250C; (17) T69C, Q195C, E80C, D224C, T337C and T423C; (18) T69C, Q195C, E80C, D224C, G111C and E323C; (19) T69C, Q195C, A211C,M250C, T337C and T423C; (20) T69C, Q195C, A211C, M250C, G111C and E323C; (21) T69C, Q195C, T337C, T423C, G111C and E323C; (22) E80C, D224C, A211C, M250C, T337C and T423C; (23) E80C, D224C, A211C, M250C, G111C and E323C; (24) E80C, D224C, T337C, T423C, G111C and E323C; and, (25) A211C, M250C, T337C, T423C, G111C and E323C.

4. The mutant according to any one of claims 1 to 3 comprising one or more further engineered disulfide mutation selected from the group consisting of G366C and D454C, T411C and Q434C, I137C and A159C, A140C and S149C, L141C and A159C, L141C and A161C, E146C and T160C, V148C and L158C and T150C and R156C.

5. The mutant according to any one of claims 1 to 4, wherein the mutant comprises one or more, preferably one, two or three, cavity filling mutations selected from group consisting of T49I, S149T, A159V, S291I, T365I and L473F.

6. The mutant according to any one of claims 1 to 5, wherein the mutant comprises one or more, preferably one, proline substitution mutation selected from the group consisting of L66P, L110P, S132P, N145P, L187P, V449P and A459P.

7. The mutant according to any one of claims 1 to 6, wherein the mutant comprises one or more, preferably one, glycine replacement mutation selected from the group consisting of G106A, G121A and G239A.

8. The mutant according to any one claims 1 to 7 wherein the mutant comprises the mutations Q100R and S101R.

9. The mutant according to claim 1 wherein (a) the mutant comprises a cysteine (C) at position 69 (69C) and at position 195 (195C), and wherein the mutant comprises a F1 polypeptide and a F2 polypeptide selected from the group consisting of: (1) a F2 polypeptide comprising the amino acid sequence of SEQ ID NO:10 and a F1 polypeptide comprising the amino acid sequence of SEQ ID NO:9; (2) a F2 polypeptide comprising an amino acid sequence that is at least 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:10 and a F1 polypeptide comprising an amino acid sequence that is at least 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:9 or; (b) the mutant comprises a cysteine (C) at position 80 (80C) and at position 224 (224C), and wherein the mutant comprises a F1 polypeptide and a F2 polypeptide selected from the group consisting of: (1) a F2 polypeptide comprising the amino acid sequence of SEQ ID NO:12 and a F1 polypeptide comprising the amino acid sequence of SEQ ID NO:11; (2) a F2 polypeptide comprising an amino acid sequence that is at least 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:12 and a F1 polypeptide comprising an amino acid sequence that is at least 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:11 or; (c) the mutant comprises a cysteine (C) at position 211 (211C) and at position 250 (250C), and wherein the mutant comprises a F1 polypeptide and a F2 polypeptide selected from the group consisting of: (1) a F2 polypeptide comprising the amino acid sequence of SEQ ID NO:14 and a F1 polypeptide comprising the amino acid sequence of SEQ ID NO:13; (2) a F2 polypeptide comprising an amino acid sequence that is at least 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:14 and a F1 polypeptide comprising an amino acid sequence that is at least 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:13 or; (d) the mutant comprises a cysteine (C) at position 337 (337C) and at position 423 (423C), and wherein the mutant comprises a F1 polypeptide and a F2 polypeptide selected from the group consisting of: (1) a F2 polypeptide comprising the amino acid sequence of SEQ ID NO:16 and a F1 polypeptide comprising the amino acid sequence of SEQ ID NO:15; (2) a F2 polypeptide comprising an amino acid sequence that is at least 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:16 and a F1 polypeptide comprising an amino acid sequence that is at least 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:15 or; (e) the mutant comprises a cysteine (C) at position 111 (111C) and at position 323 (323C), and wherein the mutant comprises a F1 polypeptide and a F2 polypeptide selected from the group consisting of: (1) a F2 polypeptide comprising the amino acid sequence of SEQ ID NO:18 and a F1 polypeptide comprising the amino acid sequence of SEQ ID NO:17; (2) a F2 polypeptide comprising an amino acid sequence that is at least 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:18 and a F1 polypeptide comprising an amino acid sequence that is at least 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:17.

10. The mutant according to any one of claims 1 to 9, wherein the F1 polypeptide lacks the entire cytoplasmic domain, or lacks the cytoplasmic domain and a portion of or all entire transmembrane domain.

11. The mutant according to any one of claims 1 to 9, wherein the F1 polypeptide comprises the ectodomain, the transmembrane domain and the cytoplasmic domain.

12. The mutant according to any one of claims 1 to 10, wherein the mutant is linked to a trimerization domain.

13. The mutant according to claim 12, wherein the trimerization domain is a phage T4 fibritin foldon.

14. The mutant according to claim 12 or 13, wherein the trimerization domain is linked to the C-terminus of the F1 polypeptide via a linker.

15. The mutant according to claim 14, wherein the linker is selected from the group consisting of GG, GS, GGGS or SAIG, preferably GGGS.

16. The mutant according to any one of claims 1 to 15, wherein the mutant is in the form of a trimer.

17. The mutant according to any one of claims 1 to 16, wherein the mutant is in the prefusion conformation.

18. The mutant of any one of claims 1 to 17 wherein the wild-type hMPV F protein is SEQ ID NO:7.

19. The mutant of any one of claims 1 to 18 wherein the wild-type hMPV is of subtype A.

20. The mutant of any one of claims 1 to 18 wherein the wild-type hMPV is of subtype B.

21. The mutant of any one of claims 1 to 20 wherein the amino acid positions correspond to the amino acid sequence of a reference of SEQ ID NO:7.

22. A nucleic acid comprising at least one coding sequence encoding at least one mutant of a wild-type hMPV F protein according to any one of claims 1 to 21, preferably claim 11, or an immunogenic fragment or immunogenic variant thereof, wherein the nucleic acid comprises at least one heterologous untranslated region (UTR).

23. The nucleic acid according to claim 22, wherein the at least one heterologous untranslated region is selected from at least one heterologous 5’-UTR and/or at least one heterologous 3’- UTR.

24. The nucleic acid according to any one of claims 22 or 23, wherein the at least one heterologous 3’-UTR comprises or consists of a nucleic acid sequence having at least, at most, exactly, or between any two of 99%, 98%, 97%, 96%, 95%, 90%, 85%, or 80% identity to CΨCGAGCΨGGΨ ACΨGCAΨGCA CGCAAΨGCΨA GCΨGCCCCΨΨ ΨCCCGΨCCΨG GGΨACCCCGA GΨCΨCCCCCG ACCΨCGGGΨC CCAGGΨAΨGC ΨCCCACCΨCC ACCΨGCCCCA CΨCACCACCΨ CΨGCΨAGΨΨC CAGACACCΨC CCAAGCACGC AGCAAΨGCAG CΨCAAAACGC ΨΨAGCCΨAGC CACACCCCCA CGGGAAACAG CAGΨGAΨΨAA CCΨΨΨAGCAA ΨAAACGAAAG ΨΨΨAACΨAAG CΨAΨACΨAAC CCCAGGGΨΨG GΨCAAΨΨΨCG ΨGCCAGCCAC ACCCΨGGAGC ΨAGC.

25. The nucleic acid according to any one of claims 22 to 24, wherein the at least one heterologous 5’-UTR comprises or consists of a nucleic acid sequence having at least, at most, exactly, or between any two of 99%, 98%, 97%, 96%, 95%, 90%, 85%, or 80% identity to GAAΨAAAC ΨAGΨAΨΨCΨΨ CΨGGΨCCCCA CAGACΨCAGA GAGAACCCGC CACC.

26. The nucleic acid according to any one of claims 22 to 25, wherein the nucleic acid comprises at least one poly(A) sequence, preferably comprising 30 to 200 adenosine nucleotides and/or at least one poly(C) sequence, preferably comprising 10 to 40 cytosine nucleotides.

27. The nucleic acid according to any one of claims 22 to 26, wherein the nucleic acid is a DNA or an RNA.

28. The nucleic acid according to any one of claims 22 to 27, wherein the nucleic acid is a coding RNA.

29. The nucleic acid according to claim 28, wherein the coding RNA is an mRNA, a self- replicating RNA, a circular RNA, or a replicon RNA.

30. The nucleic acid according to any one of claims 22 to 29, wherein the nucleic acid is an mRNA.

31. The nucleic acid according to claim 30, wherein the mRNA comprises at least one poly(A) sequence comprising 30 to 200 adenosine nucleotides and the 3’ terminal nucleotide is an adenosine.

32. The nucleic acid according to any one of claims 27 to 31, wherein the RNA, preferably the coding RNA, comprises a 5’-cap structure, preferably m7G, capO, cap1 , cap2, a modified capO or a modified cap1 structure, preferably a 5’- cap1 structure.

33. The nucleic acid according to any one of claims 27 to 32, wherein the RNA is codon- optimized.

34. The nucleic acid according to any one of claims 27 to 33, wherein the RNA comprises a chemically modified nucleotide.

35. The nucleic acid according to any one of claims 27 to 34, wherein the RNA comprises N1- methylpseudouridine substitution. Preferably, all the uridines of the RNA are replaced by N1- methylpseudouridine.

36. The nucleic acid according to any one of claims 27 to 35, wherein the RNA is a purified RNA, preferably an RNA that has been purified by RP-HPLC and/or TFF.

37. The nucleic acid according to any one of claims 27 to 36 wherein the RNA comprises the nucleic acid sequence of any of SEQ ID NO:20, SEQ ID NO:22, SEQ ID NO:24; SEQ ID NO:26 or SEQ ID NO:28.

38. A composition comprising at least one nucleic acid according to any one of claims 22 to 37.

39. The composition according to claim 38, wherein the composition comprises at least one pharmaceutically acceptable carrier.

40. The composition according to claim 38, wherein the composition comprises RNA with an RNA integrity of 70% or more.

41. The composition according to any one of claims 38 to 40, wherein the composition comprises RNA with a capping degree of 70% or more, preferably wherein at least 70%, 80%, or 90% of the mRNA species comprise a Cap1 structure.

42. The composition according to any one of claims 38 to 41, wherein the at least one nucleic acid is complexed or associated with or at least partially complexed or partially associated with one or more cationic or polycationic compound, preferably cationic or polycationic polymer, cationic or polycationic polysaccharide, cationic or polycationic lipid, cationic or polycationic protein, cationic or polycationic peptide, or any combinations thereof.

43. The composition according to any one of claims 38 to 42, wherein the at least one nucleic acid is complexed or associated with one or more lipids or lipid-based carriers, thereby forming liposomes, lipid nanoparticles (LNP), lipoplexes, and/or nanoliposomes, preferably encapsulating the at least one nucleic acid.

44. The composition according to any one of claims 38 to 43, wherein the at least one nucleic acid is complexed with one or more lipids thereby forming lipid nanoparticles.

45. The composition according to claim 44, wherein the LNP comprises a cationic lipid according to formula III-3: 46. The composition according to claim 44 or 45, wherein the LNP comprises a PEG lipid of formula (IVa): wherein n has a mean value ranging from 30 to 60, preferably wherein n has a mean value of about 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, most preferably wherein n has a mean value of 49 or 45. 47. The composition according to any one of claims 44 to 46, wherein the LNP comprises a PEG lipid of formula (IVa): wherein n is an integer selected such that the average molecular weight of the PEG lipid is about 2500g/mol. 48. The composition according to any one of claims 44 to 47, wherein the LNP comprises one or more neutral lipids and/or one or more steroid or steroid analogues. 49. The composition according to claim 48, wherein the neutral lipid is 1,2-distearoyl-sn- glycero-3-phosphocholine (DSPC), preferably wherein the molar ratio of the cationic lipid to DSPC is in the range from about 2:1 to about 8:1. 50. The composition according to claim 48 or 49, wherein the steroid is cholesterol, preferably wherein the molar ratio of the cationic lipid to cholesterol is in the range from about 2:1 to about 1 :1. 51. The composition according to any one of claims 44 to 50, wherein the LNP comprises (i) at least one cationic lipid, preferably a lipid of formula (III), more preferably lipid Ill-3; (ii) at least one neutral lipid, preferably 1 ,2-distearoyl-sn-glycero-3-phosphocholine (DSPC); (iii) at least one steroid or steroid analogue, preferably cholesterol; and (iv) at least one polymer conjugated lipid, preferably a PEG-lipid derived from formula (IVa, with n = 49), wherein (i) to (iv) are in a molar ratio of about 20-60% cationic lipid, 5-25% neutral lipid, 25-55% sterol, and 0.5-15% PEG-lipid. 52. The composition according to any one of claims 44 to 51, wherein the LNP comprises (i) at least one cationic lipid, preferably a lipid of formula (III), more preferably lipid Ill-3; (ii) at least one neutral lipid, preferably 1 ,2-distearoyl-sn-glycero-3-phosphocholine (DSPC); (iii) at least one steroid or steroid analogue, preferably cholesterol; and (iv) at least one polymer conjugated lipid, preferably a PEG-lipid derived from formula (IVa, with n = 45), wherein (i) to (iv) are in a molar ratio of about 20-60% cationic lipid, 5-25% neutral lipid, 25-55% sterol, and 0.5-15% PEG-lipid. 53. The composition according to any one of claims 44 to 52, wherein (i) to (iv) are in a molar ratio of about 50:10:38.5:1.5, preferably 47.5:10:40.8:1.7 or more preferably 47.4:10:40.9:1.7. 54. The composition according to any one of claims 44 to 53, wherein the LNP comprises (i) at least one cationic lipid; (ii) at least one neutral lipid; (iii) at least one steroid or steroid analogue; and (iv) at least one PEG-lipid, wherein (i) to (iv) are in a molar ratio of about 20- 60% cationic lipid, 5-25% neutral lipid, 25-55% sterol, and 0.5-15% PEG-lipid. 55. The composition according to any one of claims 44 to 54, wherein the LNP comprises (i) at least one cationic lipid according to formula III-3; (ii) DSPC; (iii) cholesterol; and (iv) a PEG- lipid, according to formula IVa, wherein (i) to (iv) are in a molar ratio of about 20-60% cationic lipid, 5-25% neutral lipid, 25-55% sterol, and 0.5-15% PEG-lipid. 56. The composition according to any one of claims 38 to 55, wherein the composition is a lyophilized composition. 57. An immunogenic composition comprising a mutant according to any one of claims 1 to 21, a nucleic acid according to any one of claims 22 to 37 or a composition according to any one of claims 38 to 56.