The purpose of this study is to see if 2 study vaccines, ALVAC-HIV (vCP1452) and gp160 MN/LAI-2, are safe and effective in boosting the body's attacks on HIV in HIV-positive patients.

HIV-infected patients who have been treated with anti-HIV drugs for a long time may have weakened immune responses. One way to strengthen these responses may be to have a safe and effective vaccine, which will boost immune responses that are specific to HIV.

HIV-infected patients treated with antiretroviral therapy for prolonged periods of time may show decreased levels of HIV-specific immune responses. In these patients, a prime-boost vaccine strategy may induce both humoral and cell-mediated immunity. The hypothesis of this study is that the vaccine strategy selected will be both safe and immunogenic in the patient population being tested.

Patients continue antiretroviral medications throughout the course of this study. All patients receive intramuscular injections of ALVAC-HIV (vCP 1452) and recombinant soluble gp160 MN/LAI-2 on Days 0, 30, 90, and 180. Patients are monitored for safety 30 minutes after each immunization and by telephone contact within 72 hours of each vaccination. In addition, each patient records adverse events in a diary. Patients have regular physical exams, pregnancy tests, and blood drawn for virologic and immunologic assessments. The induction of HIV-specific responses will be measured.

Inclusion Criteria

Patients may be eligible for this study if they:

• Are HIV-positive.
• Have a viral load (amount of HIV in the blood) of less than 50 copies/ml.
• Have been taking anti-HIV drugs for at least 2 years.
• Are already participating in ongoing clinical trials at the Aaron Diamond AIDS Research Center.
• Are at least 19 years old.
• Practice abstinence or use 2 barrier methods of birth control, both men and women who are able to have children.

Exclusion Criteria

Patients will not be eligible for this study if they:

• Have HIV infection that is spreading through the body even though they are taking anti-HIV drugs.
• Are breast-feeding.
• Are pregnant.
• Are allergic to eggs and/or neomycin.
• Show evidence of poor immune responses.