Participants in Groups 1 and 3 will attend additional study visits on Days 1, 3, 14, 42, 91, 98, 169, 171, 175, 182, 273, and 364. Participants in Groups 2 and 4 will attend additional study visits on Days 14, 42, 98, 182, 273, and 364. Most study visits will include a physical examination, blood collection, oral mucosa examination, interviews and questionnaires, and oral mucosa examination. If participant has any oral sores, oral swabs may be collected. Saliva also may be collected. Select study visits will include a mini mental state exam, urine collection, HIV testing, and risk reduction counseling. Study researchers will contact participants at Months 15, 24, and 36 for follow-up health monitoring.