Interventional Study of Mucosal and Antimicrobial Responses to Repeated Vaginal Applications of Tenofovir Gel in HIV Uninfected Women

Inclusion Criteria: * Normal menstrual history with regular cycles and with a minimum of 21 days between menses * Sexually abstinent or in a stable, mutually monogamous relationship with a partner who is HIV uninfected * Agree to abstain from sexual intercourse and to not use vaginal products within 48 hours of study entry and for the duration of the study Exclusion Criteria: * HIV infected * Sexually transmitted infection within 6 months of study entry * Use of nontherapeutic intravenous drugs within 12 months of study entry * Menopausal * Currently using hormonal contraception or have used hormonal contraception within 2 months of study entry * Menstruating at screening or enrollment visits * Positive urine culture * Positive chlamydia, gonorrhea, or trichomonas result at screening * Abnormal Pap smear * Clinically detectable genital abnormality. More information on this criterion can be found in the protocol. * History of toxic shock syndrome or a history of symptoms suggesting toxic shock syndrome * History of intermenstrual bleeding within 3 months of study entry * Previous gynecologic surgery or have received treatment for syphilis, genital herpes, chlamydia, gonorrhea, trichomonas, or genital warts within 6 months of study entry * Received treatment for Candida, bacterial vaginosis, or urinary tract infection within 1 month of study entry * Have douched or used vaginal products, including lubricants, feminine hygiene products, vaginal drying agents, and sex toys within 48 hours of study entry * Acute or chronic hepatitis B virus infection * Liver or kidney abnormalities * Oral antibiotics within 7 days of study entry * Pregnant, less than 6 months postpartum, or breastfeeding