Characterization of cell-surface receptors for rabies virus on BHK-21 cells
Virus infection is initiated by the attachment of an individual virion to the host cell surface in a manner that will facilitate virion uptake and productive infection. The specific interaction of viral attachment proteins with molecular constituents of the host cell surface may influence the host range and tissue tropism of a virus. Prior studies on the attachment of rabies virus to BHK-21 cells have established the specificity of rabies virus receptors on these cells based on the saturability of the receptors and on competitive binding. The purpose of this investigation was to biochemically define the receptor molecules on BHK-21 cells. Initially, the treatment of the cells with proteases prior to virus binding revealed the involvement of protein in specific virus binding sites. Subsequently, the receptor activity in fractionated solubilized BHK-21 plasma membranes was analyzed using a competition binding assay. Direct binding of the virus to solubilized proteins fractionated by gel electrophoresis and transferred to nitrocellulose was also investigated. The results of these analyses implicated a glycosylated, intrinsic cell membrane protein or protein complex with electrophoretic characteristics similar to serum fibronectin (FN) in the binding of rabies virus to BHK-21 cells. However, the putative cellular receptor protein does not bind antisera made to serum FN, nor was it possible to remove this protein from the solubilized membrane extract by gelatin affinity chromatography, a procedure used to remove fibronectin from cell extracts and from serum. This indicated that the implicated protein was not FN. However, the finding did raise the question of whether rabies virus binds to FN. This led to an analysis, using both competition assays for virus binding to and infection of BHK-21 cells and direct binding assays, of the interaction between purified radiolabelled rabies virus and serum FN. The results show that rabies virus does specifically bind to serum FN. In conclusion, while the exact identity of the protein component to which rabies virus binds on BHK-21 cells remains unknown, this analysis does document the involvement of a protein component with particular biochemical characteristics in that binding. Furthermore, analyses show that rabies virus binds serum fibronectin.
Broughan, Jane Hidalgo, "Characterization of cell-surface receptors for rabies virus on BHK-21 cells" (1991). Dissertations available from ProQuest. AAI9125601.