Characterization of V5 Tagged Rift Valley Fever Virus (RVFV) and Identification of Host Proteins That Interact with RVFV
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Saleem, Sahar
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Abstract
Rift Valley Fever Virus (RVFV) belongs to the genera Phlebovirus in the family Phenuviridae. It is an arbovirus, which can be transmitted by vector mosquitoes. RVFV infects livestock and humans. Infection of pregnant ruminants, including goats, sheep and cattle, results in high abortion rates. Rift Valley fever (RVF) ranges from subclinical to fatal and may cause fetal malformation. In adult sheep, the mortality rate is about 20% while lambs have a higher mortality rate. In humans, the incubation period for the virus is about 6-7 days and RVFV presents with a self-limiting febrile illness which includes malaise, headaches and nausea. In some cases the symptoms may progress to neurological disorders, hemorrhagic fever and/ or ocular disease. RVFV has been classified as a category A pathogen by the National Institute of Allergy and Infectious Diseases (NIAID) as it has the potential for an outbreak and poses the highest threat to national security. It is considered an overlap select agent by the Centers of Disease Control (CDC) and United States Department of Agriculture (USDA). There are currently no FDA approved therapies or vaccines available to the public for RVFV infection. It therefore is important to look at the interaction of viral proteins with host proteins so they can be targeted for therapeutics against RVFV. Gn is one of the glycoproteins of RVFV which plays an important role in the assembly of the virion. The host protein partners of RVFV Gn are largely unknown. Therefore, we aim to identify Gn protein partners using a proteomic-based approach (immunoprecipitation followed by mass spectrometry). To facilitate this analysis and to provide a tool for future research, two V5 tagged MP12 viruses were made namely V5Gn 105 and V5Gn 229 . Our data indicates that the recombinant viruses were functionally similar to the wild type MP12. Our research identified E3 Ubiquitin-protein ligase UBR4 (UBR4) as one of the host protein partners that interacts with RVFV Gn. Knockdown of UBR4 from cells decreases the viral titers from infected cells. Based on our findings that UBR4 knockdown cells have an increased retention of virions, we hypothesize that UBR4 plays a role in the egress of virions from the cells.
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This thesis has been embargoed for 2 years and will not be available until August 2020 at the earliest.
Keywords
Rift Valley Fever Virus, Bunyavirus/Phenuviridae, V5 tag, Glycoproteins, UBR4