Participants will be enrolled in this study for 1 year. Group 4 participants will receive EP HIV-1090 or placebo at study entry and Months 1, 3, and 6. There will be 11 study visits that will occur at screening; study entry; and Months 0.5, 1, 1.5, 3, 3.5, 6, 6.5, 9, and 12. A physical exam and risk reduction/pregnancy prevention counseling will occur at each visit. Participants will be asked about their adverse experiences from vaccination at each visit. Blood and urine collection will occur at selected visits.