A Phase I Trial to Evaluate the Safety and Immunogenicity of rMVA-HIV (rMVA-HIV Env/Gag + rMVA-HIV Tat/Rev/Nef-RT) and rFPV-HIV (rFPV-HIV Env/Gag + rFPV-HIV Tat/Rev/Nef-RT) Vaccines, Alone or in Combination, in Healthy, Vaccinia Naive HIV-1 Negative Participants

Pox viruses are used for investigational vaccines in humans because they can accommodate large amounts of foreign DNA, can infect mammalian cells, and can access the cytotoxic T-cell responses believed to be important in the control of HIV infection and disease. Two pairs of matching recombinant HIV vaccines have been developed for use in this study. One pair uses a modified vaccinia Ankara (MVA) vector and the other pair uses a fowlpox vector (FPV). Each vaccine pair consists of one vaccine containing env/gag sequences and one vaccine containing modified tat/rev/nef-RT sequences. The HIV sequences are identical and are from a vertically transmitted pediatric primary isolate. The controls in this study are MVA vectors and FPVs without the HIV genes. The study will evaluate the safety and immunogenicity of the vaccine pairs. There are two parts to this study. Participants in Part A will be randomly assigned to one of five different vaccination groups. Within each group, participants will be randomly assigned to receive either vaccine or control injections. Group 1 participants will receive the FPV vaccine pair or FPV control at each vaccine visit. Groups 2, 3, and 4 will receive one of three different doses of the MVA vaccine pair or MVA control at study entry and Month 1, then a fixed dose of the FPV vaccine pair or FPV control at Months 3, 5, and 7. Group 5 participants will receive the MVA vaccine pair or MVA control at maximum tolerated dose (MTD) at each vaccine visit. Groups 1 and 2 will enroll simultaneously; Groups 3, 4, and 5 will enroll as safety data from the previous groups become available. In Part B, participants will be randomly assigned to receive study vaccine or control vaccine in one of three vaccination groups. Group 6 participants will receive the FPV vaccine pair or FPV control at each vaccine visit. Group 7 participants will receive the MVA vaccine pair or MVA control at study entry and Month 1, then a fixed dose of the FPV vaccine pair or FPV control at Months 3, 5, and 7. Group 8 participants will receive the MVA vaccine pair at MTD or MVA control at each vaccine visit. Enrollment into Groups 6, 7, and 8 will begin simultaneously after the completion of the safety data evaluation of Groups 1 and 2. Study vaccinations will be given at study entry and at Months 1, 3, 5 and 7. Tests for cardiac injury will be performed at screening and at each 2-week follow-up visit after vaccination. Participants will have an electrocardiogram (ECG) at screening and 2 weeks after the first and last vaccinations. Study visits will occur at screening, study entry, and at 11 visits over 13 months. Study visits will consist of a physical exam, risk reduction/pregnancy prevention counseling, cardiac symptom assessment, and blood and urine collection. Women will have pregnancy tests at study entry and Months 1, 3, 5, 7, and 13.