 There are two parts to this study. Part A will last 12 months. In Part A, 48 participants will be randomly assigned to 1 of 4 groups in sequential order dose escalation. All participants will receive 3 vaccinations. Group 1 will receive 3 vaccinations of the HIV-1 gag DNA vaccine or placebo. Group 2 will receive 3 vaccinations of either the HIV-1 gag DNA vaccine with a low dose of IL-15 adjuvant or a placebo. Group 3 will receive 3 vaccinations of either the HIV-1 gag vaccine with a medium dose of IL-15 adjuvant or a placebo. Group 4 will receive 3 vaccinations of either the HIV-1 gag vaccine with a high dose of IL-15 adjuvant or a placebo. Vaccinations will be given at Months 0, 1, and 3. There will be 11 study visits in Part A. A physical exam, pregnancy prevention counseling, medication history, and adverse event reporting will occur at most visits. Urine and blood collection will occur at some visits. Participants will also be asked to complete questionnaires at certain visits. 