VACCINE-INDUCED ANTIBODIES TO NATIVE AND RECOMBINANT HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 ENVELOPE GLYCOPROTEINS

The ability of antibody induced by combination vaccination (human immu nodeficiency virus type 1 (HIV-1(LAV)) gp160 live recombinant vaccinia virus priming followed by a booster injection with a baculovirus-expr essed HIV-1(LAV) recombinant gp160 candidate vaccine) to bind to nativ e and recombinant HIV-1 envelope glycoproteins was measured in 12 unin fected healthy adult volunteers. By using a flow cytometric indirect i mmunofluorescence assay (FIFA) to detect vaccine-induced antibody to n ative envelope glycoprotein expressed by target cells infected with HI V-1(IIIB) (infected-cell FIFA), sera from ten of 12 vaccinees before t he rgp160 booster injection were positive, and all vaccinees were posi tive at higher levels after the rgp160 boost. Evidence for cross-react ing antibody to HIV-1(MN), HIV-1(RF) and HIV-1(CC) expressed on infect ed cells was also present after the rgp160 booster injection. High tit res of anti-rgp160 antibody were also measured in an enzyme-linked imm unosorbent assay after the boost. None of the sera obtained immediatel y prior to the rgp160 booster injection, but all sera drawn after the boost, reacted with recombinant gp160 antigen bound to uninfected cell surfaces. The high anti-gp160 binding activity in these assays, the c oncomitant presence of positivity in infected-cell and rgp160-coated c ell FIFA assays, and high anti-rgp160 antibody titre by ELISA in sera from recipients of this prime-boost vaccination regimen suggest that t he live vector priming and rgp160 boosting strategy should be pursued in HIV-1 vaccine development.