NEUTRALIZATION OF SYNCYTIUM-INDUCING PRIMARY ISOLATES BY SERA FROM HUMAN-IMMUNODEFICIENCY-VIRUS (HIV)-UNINFECTED RECIPIENTS OF CANDIDATE HIV VACCINES

Most candidate human immunodeficiency virus (HIV)-1 vaccines induce an tibodies that neutralize T cell line-adapted HIV-1 strains. Until rece ntly, however, no neutralizing activity against primary HIV-1 isolates had been demonstrated in sera from human vaccinees, Since most candid ate HIV-1 vaccines have been constructed from T cell line-adapted sync ytium-inducing (SI) strains, experiments were done to test whether ser a from recipients of SI-based vaccines could preferentially neutralize SI primary HIV-1 isolates, Various neutralization assays were perform ed with sera from volunteers receiving ALVAC(gp160MN) and/or rgpl20(SF 2). Neutralizing activity was detected against 4 of 8 SI primary isola tes but against none of 5 non-SI primary isolates, The data suggest th at, for the induction of neutralizing antibodies to a broad array of H IV-1 primary isolates, a polyvalent vaccine will be needed containing representatives of more than a single category of viruses.