 Part B will consist of 96 participants, enrolled in 3 groups. Participants in Part B will receive their first vaccination 2 weeks after Part A participants receive their second vaccination. Group 5 participants will receive either the HIV-1 gag DNA vaccine or placebo. Group 6 participants will receive either the HIV-1 gag DNA vaccine plus IL-12 DNA or placebo. Vaccinations for Groups 5 and 6 will occur at study entry and at Months 1, 3, 6, and 9. Group 7 participants will receive either the gag DNA vaccine plus IL-12 DNA or placebo at study entry and at Months 1 and 3. Throughout the study, blood and urine collections will occur, physical exams will be conducted, HIV testing and counseling will be offered, and interviews and questionnaires will be completed. 