IDENTIFICATION OF THE GENE ENCODING VACCINIA VIRUS IMMUNODOMINANT PROTEIN P35

The major envelope protein, p35, of vaccinia virus (VV; strain LIVP) w as purified by extraction from virions with the non-ionic detergent No nidet P-40. The protein was cleaved with CNBr. Four homogeneous peptid es were isolated and their N-terminal amino-acid (aa) sequences determ ined. A computer search of a protein sequence databank revealed comple te identity of the determined sequences with aa 44-63, 144-149, 154-16 5 and 224-238 of ORF H3 of the HindIII-H fragment of the VV genome [Ro sel et al., J. Virol. 60 (1989) 436-446]. Earlier, Gordon et al. [Viro logy 167 (1988) 361-369] determined that the p35 surface protein of VV strain IHD-W is encoded by the H6 gene. Muravlev et al. [Biopolymery i kletka 6 (1990) 83-89 (Russian)] deduced from their data that gene A 2 encodes this prominent antigen. Taking into account this ambiguity, we cloned the genes H3, H6 and A2 in expression vectors, prepared the specific antisera against the expression products and conducted the im munochemical analysis of the recombinant and native VV-specific protei ns. It has been established that the H6 codes for an early protein tha t is found only in the infected cell extracts, but is absent in mature virions. The immunodominant protein p35 of VV strain LIVP is encoded by the gene H3. The gene A2 protein product is present mainly in the i nfected cell extract, but the antiserum against the A2 product shows a rather weak interaction with the 35-kDa fraction of structural VV pro teins resolved by electrophoresis.