Participants apply PRO 2000/5 gel intravaginally either once or twice daily for 14 days. HIV-negative participants in sexually active cohorts (Cohorts A1-A4) are instructed to engage in vaginal intercourse at least twice a week. Participants in the HIV-positive cohort (Cohort B1) abstain from sexual intercourse for the dosing period. Researchers conduct physical exams to see if the gel is having any harmful effects on the woman's vulva, vagina, or cervix. Women and their male partners are questioned about gel usage.