A Phase I Study of the Safety and Immunogenicity of rgp120/HIV-1IIIB Vaccine in Healthy Adult Subjects (NOTE: Study Extended ONLY for Subjects Who Have Previously Received rgp120/HIV-1IIIB or rgp120/HIV-1MN on VEU 006 or VEU 006 Rollover Study)

AMENDED 11/17/93: To determine whether the pattern of response to MN rgp120 vaccine is altered by pre-exposure to IIIB rgp120. ORIGINAL DESIGN: To evaluate the safety (clinical and immunologic) of rgp120/HIV-1IIIB vaccine (gp120 vaccine) immunization in healthy HIV-1 seronegative adult subjects. To compare the immune response to 100 mcg gp120 vaccine versus 300 mcg gp120 vaccine. To determine whether gp120 vaccine immunization causes a significant immune response as defined by specific parameters (e.g., induction of neutralizing antibodies to the IIIB isolate of HIV-1, gp120 antigen-specific lymphocytic proliferation). Recent evidence suggests that gp120 is the HIV-1 protein with the greatest potential as a vaccine against HIV-1 infection. The gp120 envelope protein may be produced by recombinant DNA technology, and studies have shown that the vaccine is capable of eliciting neutralizing antibody activity in both rodents and nonhuman primate species. Recent evidence suggests that gp120 is the HIV-1 protein with the greatest potential as a vaccine against HIV-1 infection. The gp120 envelope protein may be produced by recombinant DNA technology, and studies have shown that the vaccine is capable of eliciting neutralizing antibody activity in both rodents and nonhuman primate species. AMENDED 11/17/93: Selected subjects from VEU 006 or VEU 006 Rollover study will receive two injections of MN rgp120 vaccine, administered 28 days apart beginning 10-16 months after their last injection. Eight additional clinic visits will be required. Subjects are followed for at least 6 months. ORIGINAL DESIGN: Twenty-eight subjects will be randomized to receive 100 or 300 mcg rgp120/HIV-1IIIB vaccine (gp120 vaccine) or matching placebo. For each dose level, 10 subjects will receive vaccine and four subjects will receive matching placebo. Injections are given intramuscularly at 0, 4, and 32 weeks. Each subject receiving treatment at the lower dose level must be monitored for unacceptable toxicity for at least 2 weeks following the initial immunization before his or her second dose is administered and before treatment at the higher dose level begins. Subjects are followed for at least 12 months.