Although recent advances have been made in antiviral therapy against AIDS, there is currently no cure for AIDS. It is likely that ultimate control of the disease depends on the development of safe and effective vaccines against HIV.

Healthy, adult volunteers without identifiable high-risk behavior for HIV-1 infection are vaccinated. In phase 1, at each participating unit, four volunteers receive a dose of gp160 (12.5 mcg); two volunteers receive placebo. Volunteers are monitored 1 month before proceeding to the second phase. In phase 2, four volunteers receive gp160 (50 mcg); two volunteers receive placebo. Primary immunization and two booster immunizations at day 30 and day 180 are done in an outpatient setting. Volunteers are closely monitored for the first 2 weeks postimmunization (primary and boosters), and extensively followed for a minimum of 2 years. Volunteers may be offered an additional boost of the same preparation at 18 months. Per 07/28/92 amendment, 18 volunteers will receive 200 mcg gp160 in an unblinded study. Volunteers in phase 2 who received four doses of 50 mcg gp160 receive an additional boost of 200 mcg gp160 at 18-19 months post initial vaccination. Per 05/13/94 amendment, volunteers in phase 2 who received the additional 200 mcg boost receive another 200 mcg boost 18-24 months after the last injection (St. Louis University site only).