Papers by Levon Abrahamyan
Frontiers in Immunology, Mar 28, 2023
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Frontiers in Microbiology, 2017
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www.mdpi.com/journal/viruses
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Frontiers in Microbiology
Since the end of 2019, the world has been challenged by the coronavirus disease 2019 (COVID-19) p... more Since the end of 2019, the world has been challenged by the coronavirus disease 2019 (COVID-19) pandemic. With COVID-19 cases rising globally, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to evolve, resulting in the emergence of variants of interest (VOI) and of concern (VOC). Of the hundreds of millions infected, immunodeficient patients are one of the vulnerable cohorts that are most susceptible to this virus. These individuals include those with preexisting health conditions and/or those undergoing immunosuppressive treatment (secondary immunodeficiency). In these cases, several researchers have reported chronic infections in the presence of anti-COVID-19 treatments that may potentially lead to the evolution of the virus within the host. Such variations occurred in a variety of viral proteins, including key structural ones involved in pathogenesis such as spike proteins. Tracking and comparing such mutations with those arisen in the general population ma...
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Frontiers in Veterinary Science, 2021
African swine fever (ASF) is an emerging viral contagious disease affecting domestic pigs (DP) an... more African swine fever (ASF) is an emerging viral contagious disease affecting domestic pigs (DP) and wild boar (WB). ASF causes significant economic damage to the pig industry worldwide due to nearly 100% mortality and the absence of medical treatments. Since 2019, an intensive spread of ASF has been observed in the Russian Far East region. This spread raises concerns for epidemiologists and ecologists given the potential threat to the WB population, which is an essential member of the region's wild ungulates and provides a notable share of food resources for predatory species. This study aims to determine the genotype of ASF virus circulating in the region, reveal the spatio-temporal patterns of the ASF outbreaks' emergence, and assess the potential reduction of the regional fauna because of expected depopulation of WB. The first historical case of ASF in the study region was caused by an African swine fever virus (ASFV) isolated from DPs and belonging to Genotype 2, CVR1; IG...
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BioNanoScience, 2019
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Virology, 2008
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RNA, 2008
The HIV-1 ribonucleoprotein (RNP) contains the major structural protein, pr55Gag, viral genomic R... more The HIV-1 ribonucleoprotein (RNP) contains the major structural protein, pr55Gag, viral genomic RNA, as well as the host protein, Staufen1. In this report, we show that the nonsense-mediated decay (NMD) factor UPF1 is also a component of the HIV-1 RNP. We investigated the role of UPF1 in HIV-1-expressing cells. Depletion of UPF1 by siRNA resulted in a dramatic reduction in steady-state HIV-1 RNA and pr55Gag. Pr55Gag synthesis, but not the cognate genomic RNA, was efficiently rescued by expression of an siRNA-insensitive UPF1, demonstrating that UPF1 positively influences HIV-1 RNA translatability. Conversely, overexpression of UPF1 led to a dramatic up-regulation of HIV-1 expression at the RNA and protein synthesis levels. The effects of UPF1 on HIV-1 RNA stability were observed in the nucleus and cytoplasm and required ongoing translation. We also demonstrate that the effects exerted by UPF1 on HIV-1 expression were dependent on its ATPase activity, but were separable from its role...
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PLoS ONE, 2013
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Journal of Virology, 2004
Effects of the cytoplasmic tail (CT) of human immunodeficiency virus type 1 Env on the process of... more Effects of the cytoplasmic tail (CT) of human immunodeficiency virus type 1 Env on the process of membrane fusion were investigated. Full-length Env (wild type [WT]) and Env with its CT truncated (ΔCT) were expressed on cell surfaces, these cells were fused to target cells, and the inhibition of fusion by peptides that prevent Env from folding into a six-helix bundle conformation was measured. For both X4-tropic and R5-tropic Env proteins, ΔCT induced faster fusion kinetics than did the WT, and peptides were less effective at inhibiting ΔCT-induced fusion. We tested the hypothesis that the inhibitory peptides were less effective at inhibiting ΔCT-induced fusion because ΔCT folds more quickly into a six-helix bundle. Early and late intermediates of WT- and ΔCT-induced fusion were captured, and the ability of peptides to block fusion when added at the intermediate stages was quantified. When added at the early intermediate, the peptides were still less effective at inhibiting ΔCT-indu...
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Journal of Virology, 2003
A mutant human immunodeficiency virus (HIV) envelope protein (Env) with an engineered disulfide b... more A mutant human immunodeficiency virus (HIV) envelope protein (Env) with an engineered disulfide bond between the gp120 and gp41 subunits (SOS-Env) was expressed on cell surfaces. With the disulfide bond intact, these cells did not fuse to target cells expressing CD4 and CCR5, but the fusion process did advance to an intermediate state: cleaving the disulfide bond with a reducing agent after but not before binding to target cells allowed fusion to occur. Through the use of an antibody directed against CCR5, it was found that at the intermediate stage, SOS-Env had associated with coreceptors. Reducing the disulfide bond after this intermediate had been reached resulted in hemifusion at low temperature and fusion at physiological temperature. The addition of C34 or N36, peptides that prevent six-helix bundle formation, at the hemifused state blocked the fusion that would have resulted after raising the temperature. Thus, Env has not yet folded into six-helix bundles after hemifusion ha...
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Journal of Virological Methods, 2005
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Journal of Cell Science, 2010
Human immunodeficiency virus type 1 (HIV-1) Gag selects for and mediates genomic RNA (vRNA) encap... more Human immunodeficiency virus type 1 (HIV-1) Gag selects for and mediates genomic RNA (vRNA) encapsidation into progeny virus particles. The host protein, Staufen1 interacts directly with Gag and is found in ribonucleoprotein (RNP) complexes containing vRNA, which provides evidence that Staufen1 plays a role in vRNA selection and encapsidation. In this work, we show that Staufen1, vRNA and Gag are found in the same RNP complex. These cellular and viral factors also colocalize in cells and constitute novel Staufen1 RNPs (SHRNPs) whose assembly is strictly dependent on HIV-1 expression. SHRNPs are distinct from stress granules and processing bodies, are preferentially formed during oxidative stress and are found to be in equilibrium with translating polysomes. Moreover, SHRNPs are stable, and the association between Staufen1 and vRNA was found to be evident in these and other types of RNPs. We demonstrate that following Staufen1 depletion, apparent supraphysiologic-sized SHRNP foci are...
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Journal of Biological Chemistry, 2009
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Journal of Virology, 2007
Human immunodeficiency virus type 1 (HIV-1) requires the sequential activities of virus-encoded p... more Human immunodeficiency virus type 1 (HIV-1) requires the sequential activities of virus-encoded proteins during replication. The activities of several host cell proteins and machineries are also critical to the completion of virus assembly and the release of infectious virus particles from cells. One of these proteins, the double-stranded RNA-binding protein Staufen1 (Stau1), selectively associates with the HIV-1 genomic RNA and the viral precursor Gag protein, pr55 Gag . In this report, we tested whether Stau1 modulates pr55 Gag assembly using a new and specific pr55 Gag oligomerization assay based on bioluminescence resonance energy transfer (BRET) in both live cells and extracts after cell fractionation. Our results show that both the overexpression and knockdown of Stau1 increase the pr55 Gag -pr55 Gag BRET levels, suggesting a role for Stau1 in regulating pr55 Gag oligomerization during assembly. This effect of Stau1 on pr55 Gag oligomerization was observed only in membranes, a...
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Additional file 1. The TRS sequences of structural genes in the HP-PRRSV/SD16 genome (GenBank: JX... more Additional file 1. The TRS sequences of structural genes in the HP-PRRSV/SD16 genome (GenBank: JX087437).
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Frontiers in Veterinary Science, 2021
African swine fever (ASF) is an emerging viral contagious disease affecting domestic pigs (DP) an... more African swine fever (ASF) is an emerging viral contagious disease affecting domestic pigs (DP) and wild boar (WB). ASF causes significant economic damage to the pig industry worldwide due to nearly 100% mortality and the absence of medical treatments. Since 2019, an intensive spread of ASF has been observed in the Russian Far East region. This spread raises concerns for epidemiologists and ecologists given the potential threat to the WB population, which is an essential member of the region's wild ungulates and provides a notable share of food resources for predatory species. This study aims to determine the genotype of ASF virus circulating in the region, reveal the spatio-temporal patterns of the ASF outbreaks' emergence, and assess the potential reduction of the regional fauna because of expected depopulation of WB. The first historical case of ASF in the study region was caused by an African swine fever virus (ASFV) isolated from DPs and belonging to Genotype 2, CVR1; IG...
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Pathogens
At the end of 2019, the world was struck by the COVID-19 pandemic, which resulted in dire repercu... more At the end of 2019, the world was struck by the COVID-19 pandemic, which resulted in dire repercussions of unimaginable proportions. From the beginning, the international scientific community employed several strategies to tackle the spread of this disease. Most notably, these consisted of the development of a COVID-19 vaccine and the discovery of antiviral agents through the repositioning of already known drugs with methods such as de novo design. Previously, methylthiomorphic compounds, designed by our group as antihypertensive agents, have been shown to display an affinity with the ACE2 (angiotensin converting enzyme) receptor, a key mechanism required for SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) entry into target cells. Therefore, the objective of this work consists of evaluating, in silico, the inhibitory activity of these compounds between the ACE2 receptor and the S1 subunit of the SARS-CoV-2 spike protein. Supported by the advances of different research g...
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Viruses
Aleutian mink disease virus (AMDV) is known to cause the most significant disease in the mink ind... more Aleutian mink disease virus (AMDV) is known to cause the most significant disease in the mink industry. It is globally widespread and manifested as a deadly plasmacytosis and hyperglobulinemia. So far, measures to control the viral spread have been limited to manual serological testing for AMDV-positive mink. Further, due to the persistent nature of this virus, attempts to eradicate Aleutian disease (AD) have largely failed. Therefore, effective strategies to control the viral spread are of crucial importance for wildlife protection. One potentially key tool in the fight against this disease is by the immunization of mink against AMDV. Throughout many years, several researchers have tried to develop AMDV vaccines and demonstrated varying degrees of protection in mink by those vaccines. Despite these attempts, there are currently no vaccines available against AMDV, allowing the continuation of the spread of Aleutian disease. Herein, we summarize previous AMDV immunization attempts in...
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Retrovirology
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Papers by Levon Abrahamyan