The combination of a live recombinant primer followed by a subunit boost has the potential to induce not only cytotoxic T lymphocytes but also neutralizing antibody.

Volunteers are randomized to one of seven groups to receive immunizations with either ALVAC-HIV vCP300 or ALVAC-RG vCP65 (control), plus simultaneous or sequential boosting with rgp120/HIV-1SF2 or placebo. Immunizations are given at 0, 1, 6, and 9 months or 0, 1, 3, and 6 months. Volunteers are followed for at least 24 months.

Inclusion Criteria

Volunteers must have:

• Normal history and physical exam.
• ELISA and Western blot negative for HIV.
• CD4 count >= 400 cells/mm3.
• Normal urine dipstick with esterase and nitrite.
• Lower risk sexual behavior.

Exclusion Criteria

Co-existing Condition:

Subjects with the following symptoms or conditions are excluded:

• Positive hepatitis B surface antigen.
• Medical or psychiatric condition (such as recent suicidal ideation or present psychosis) that precludes compliance.
• Active syphilis. NOTE: Subjects with serology documented to be a false positive or due to a remote (> 6 months) treated infection are eligible.
• Active tuberculosis. NOTE: Subjects with a positive PPD and a normal chest x-ray showing no evidence of TB and not requiring isoniazid therapy are eligible.
• Allergy to egg products or neomycin.

Subjects with the following prior conditions are excluded:

• History of immunodeficiency, chronic illness, autoimmune disease, or use of immunosuppressive medications.
• History of anaphylaxis or other serious adverse reactions to vaccines.
• Prior immunization against rabies.
• History of serious allergic reaction to any substance, requiring hospitalization or emergent medical care (e.g., Stevens-Johnson syndrome, bronchospasm, or hypotension).
• Prior psychiatric condition (such as history of suicide attempts or past psychosis) that precludes compliance.
• History of cancer unless there has been surgical excision that is considered to have achieved cure.

Prior Medication:

Excluded:

• Live attenuated vaccines within 60 days prior to study entry. NOTE: Medically indicated killed or subunit vaccines (e.g., influenza, pneumococcal) do not exclude if administered at least 2 weeks from HIV immunizations.
• Experimental agents within 30 days prior to study entry.
• Prior HIV vaccines.
• Prior rabies immunization.

Prior Treatment:

Excluded:

• Blood products or immunoglobulin within 6 months prior to study entry. Identifiable high-risk behavior for HIV infection, such as
• injection drug use within past 12 months.
• higher or intermediate risk sexual behavior.