Association of a cellular 21-kDa transmembrane protein (VAP21) with enveloped viruses

We reported previously that the rabies virions contained a 21-kDa cellular transmembrane protein (referred to as VAP21) as a minor component (Sagara, J, et al, Microbiol, Immunol, 41(12): 947-955, 1997), Zn this study, we fur ther examined the possible interactions of VAP21 with other enveloped virus es, including the vesicular stomatitis virus (VSV; negative-stranded RNA vi rus), Sindbis virus (positive-stranded RNA virus) and herpes simplex virus type 1 (HSV-1; double-stranded DNA virus). An immunoblot analysis demonstra ted that all of these enveloped viruses contained VAP21 in the virion as a minor component. Immunoprecipitation studies suggested that VAP21 was assoc iated with certain viral proteins in the cell, such as the matrix (M) prote in of VSV, a capsid protein of Sindbis virus, and at least a capsid protein (VP5) of HSV-1, The association was disrupted by treatment with 0.5% sodiu m dodecyl sulfate, but resistant to the treatment with 1% NP-40 plus 1% deo xycholate, These results suggest that: 1) VAP21 is not primarily associated with the viral transmembrane glycoprotein but rather with the internal vir al protein, and, 2) this association would cause the efficient incorporatio n of VAP21 into the virion.