EXPRESSION OF BIOLOGICALLY-ACTIVE ENVELOPE GLYCOPROTEIN FROM THE ACUTELY PATHOGENIC SIMIAN IMMUNODEFICIENCY VIRUS SIV(SMMPBJ)

The full-length envelope (env) gene from the most acutely pathogenic p rimate lentivirus described so far, the simian immunodeficiency virus SIVsmmPBj14 was expressed by a recombinant vaccinia virus vector (vv-e nv4) and was completely characterized as a previous step for its use a s an immunogen in vaccination trials. Radioimmunoprecipitation and Wes tern blot experiments indicated that SIVsmmPBj gp160 precursor was pro cessed into gp120 and gp41 subunits, and that gp 120 was released into the medium. Flow cytometry analysis showed that recombinant SIVsmmPBj was transported to and expressed on the surface of vvenv4-infected ce lls. Biochemical analysis of virus-like particles produced by coinfect ion of cells with recombinant vaccinia viruses expressing SIVsmmPBj En v (vv-env4) and Gag (vv-wtgag) proteins revealed that the Env glycopro tein was incorporated into core-like particles. Furthermore, cells exp ressing SIVsmmPBj env gene products were found to undergo fusion with the same CD4(+) cell lines in which the whole provirus has been shown to form syncytia.