Determinants Of Vesicular Stomatitis Virus And Coronavirus Fusion
Vesicular stomatitis virus (VSV) is the prototypic and best-studied member of the Rhabdoviridae. Despite this, there remain many uncertainties regarding the exact process by which VSV enters host cells. One proposed mechanism involves virus internalization into endosomes, followed by a two-step fusion reaction; initial fusion with internal vesicles of multivesicular endosomes followed by subsequent backfusion of these vesicles into the cytoplasm. However, the biological rationale for this pathway remains obscure. One feature of the internal vesicles of late endosomes is that they uniquely contain the lipid lysobisphosphatidic acid (LBPA). Using a FRETbased in vitro lipid mixing assay, we show that the presence of LBPA significantly increases the rate of VSV G-mediated membrane fusion. The increased rate of lipid mixing was selective for VSV and was not evident when other viruses, such as influenza, were examined in the same assay. These data provide a biological rationale for a two-step fusion reaction during VSV entry, and suggests that LBPA may preferentially affect the ability of VSV G (a class III viral fusion protein) to mediate lipid mixing during membrane fusion. The Coronaviridae is a virus family with significant potential to negatively affect the human population. An improvement in our understanding of the entry mechanism of these viruses could assist in the development of therapeutics. Here we characterize a proposed fusion peptide in several members of the coronavirus family. Our results show that this peptide is capable of promoting membrane fusion in a liposome based assay. When the sequence of the hypothesized fusion peptide is manipulated, its ability to promote lipid mixing is abolished. Additionally, we outline significant differences between the fusion peptides of several different coronavirus family members and postulate the effect these differences have on virus fusion. Our results support the hypothesis that this region is in fact the fusion peptide for the coronavirus family.
dissertation or thesis