RU2085582C1 - Strain of chicken herpes virus as a component for preparing bivalent vaccine for mareck disease control - Google Patents

Abstract

FIELD: veterinary virology and biotechnology. SUBSTANCE: invention relates to new vaccine strain of chicken herpes virus "42"-DEP that is able to enhance immunogenic activity of strain "FS=126" of turkey herpes virus at its using as the second (enhancing) component in the process of preparing bivalent vaccine for Mareck disease control. EFFECT: new vaccine strain indicated above, enhanced effectiveness of the strain. 1 tbl

Description

 The invention relates to veterinary virology and biotechnology and can be used in the manufacture of a vaccine against Marek's disease (BM).

 For the prevention of Marek’s disease, liquid and lyophilized vaccines are used, made from the strain FS-126 of turkey herpes virus (HVI), which protect the bird from the disease (vaccination efficiency 76-85%).

 The use of vaccines from the strain of VGI prevents the development of tumors in birds up to 100-1200 days of age.

 The aim of the present invention is to obtain a new vaccine strain of chicken herpes virus "42" -DEP, capable of increasing the immunogenic activity of the strain "FS-126" FGI when used as a second (enhancing) component in the manufacture of a bivalent vaccine against BM, while the duration of immunity hens doubles.

 The chicken herpes virus strain was obtained in a safe poultry farm from a healthy bird of 200 days of age, which does not have antibodies to HHI, but has antibodies to the herpes virus of the second serotype.

 The strain of herpes virus "42" -DEP, introduced intramuscularly by SP-day-old chickens, isolated for 16 days from the feather follicle epithelium, was adapted to the fibroblast cell culture of chicken SPF embryos with subsequent identification in ELISA with specific serum.

 The strain of chicken herpes virus is deposited in the collection of the All-Russian State Research Institute for Control, Standardization and Certification of Veterinary Medicines at number 42, the Herpesviridal family of the genus Thetalymphocryptovirus is a species of chicken herpes virus 2 serotype.

 The strain of chicken herpes virus "42" -DEP is characterized by the following symptoms and properties.

 Morphological signs. Based on comparative electron-microscopic radiation of the production strain FS-126 VGI and strain VKH "42" -DEPT during their reproduction in cell culture, the characteristics of both strains are identical. These viruses went through the ontogenetic cycle of development in the nucleoplasm, the final stages of morphogenesis. The intranuclear development cycle included the stages of the viroplast, nucleoid, nucleotide assembly, and the formation of an external supercapsid membrane. The most common form present at all stages of cultivation is a nucleocapsid with a nucleoid represented by a dense formation enclosed in a capsid protein coat.

 During electron microscopic examination, the strain "42" -ER is represented by virions typical of herpes viruses of group B, having icosahedral symmetry, the nucleocapsid contains DNA. In the nucleus of the affected cell, the virion has a value of 150-170 nm, in the cytoplasm its size increases due to the protein membrane to 200-250 nm.

Cultural signs. Strain "42" -DEP actively propagates in the primary culture of fibroblasts of SPF chicken embryos, while exhibiting a pronounced cytopathic effect, the formation of characteristic foci consisting of refractory round cells (polykaryocytes). Focus sizes reach 0.2-0.5 mm. During consecutive passages in the culture of fibroblasts of CP chicken embryos, the infectious titer of the virus increases and reaches the limits of 1x10 ³ 1x10 ⁵ CFU / ml (focus-forming units).

 When the 6-day-old SPF chicken embryos are infected in the yolk sac, the strain "42" -DEP causes their death to 20% on 3-5 days of incubation. Fallen embryos note: stunting, hepatitis, enlarged spleen and kidneys. On the chorioallantoic membrane, gray-white star-shaped plaques of 1-2 mm in size are formed. With subsequent passage in embryos, the above symptoms do not occur.

 Virulent properties. Strain "42" -DEPA is apatogenous for day old chickens.

 Antigenic properties. Strain "42" -DEPT is antigenically related to herpes viruses of groups B 1 and 3 of serotypes.

 When introduced into the body, it causes latent viremia. Antibodies to this virus are found in the blood of chickens by 60-90 days, with a further increase by 120-180 days, which enhances the bird's immune response when using this strain when vaccinating chickens with turkey herpes virus.

Immunogenic properties. Strain "42" -DEP does not have immunogenic properties when vaccinating chickens, but when using it as a second component for a bivalent vaccine, the immunogenicity of strains of VGI increases and the vaccination efficiency increases to 98.2%
Example. Conducting comparative immunogenic activity of the vaccine against Marek’s disease. Immunogenicity is determined on day-old chickens in poultry farming unsuccessful due to Marek’s disease, for which 3 groups of chickens of 1,200 heads each are formed.

 Chickens of group 1 are vaccinated with a vaccine from the strain "FS-126" (lyophilized commercial vaccine) at a dose of 2000 FOU / goal. The second group is inoculated with a bivalent vaccine consisting of a strain of FS-126 at a dose of 2000 CFU / goal and a strain of 42-DEPT at a dose of 300 CFU / goal. The third group is inoculated with the virus of strain "42" -DEPT at a dose of FOE / goal.

 Experienced birds are monitored for 240 days, given the death of a bird with signs of Marek's disease.

 The results of the studies are presented in the table.

 From the data presented in the table it can be seen that the bivalent vaccine from strain FS-126 and strain 42-DEPT has a higher immunogenicity (98.2%) than the vaccine from strain FS-126 (80.0%) and strain "42" -DEPT has practically no immunogenicity.

Claims (1)

 The strain of chicken herpes virus VGNKI N 42 as a component for the manufacture of a bivalent vaccine against Marek's disease.

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