INDUCTION OF HIV-1-NEUTRALIZING AND SYNCYTIUM-INHIBITING ANTIBODIES IN UNINFECTED RECIPIENTS OF HIV-1(IIIB) RGP120-SUBUNIT VACCINE

A recombinant human immunodeficiency virus 1 IIIB(HIV-1IIIB) gp120 sub unit vaccine (IIIB-rgp120/HIV-1, Genentech) was tested for safety and immunogenicity in a randomised, double-blind, placebo-controlled phase -I trial. HIV-1-seronegative adult volunteers received three 100 mug o r 300 mug doses of IIIB-rgp120/HIV-1 in alum adjuvant (10 vaccinees in each group), or alum adjuvant alone (8 vaccinees), at 0, 4, and 32 we eks by intramuscular injection. The three injections were well tolerat ed in both vaccine groups. Antibodies that neutralised homologous HIV- 1IIIB were induced in 9 of 10 recipients after three 300 mug doses, an d 6 of these 9 sera also neutralised heterologous HIV-1SF2. A dose res ponse was evident, since three 100 mug injections induced lower titres of HIV-1IIIB neutralising antibodies and in fewer recipients (5 of 9) than the higher dose, with no neutralisation of HIV-1SF2. Similarly, syncytia-inhibiting, CD4-rgp120-blocking, and HIV-1IIIB V3-binding ant ibodies were induced in a dose dependent manner. Response to the 300 m ug per dose vaccination occurred in a larger proportion of volunteers and at higher mean titres than seen in previous human trials with othe r recombinant envelope subunit vaccines or live vaccinia-env priming f ollowed by envelope subunit boosting.