Pre-Exposure Prophylaxis (PrEP) Adherence Monitoring Using Dried Blood Spots

Inclusion Criteria: 1. Ambulatory 18-50 year old adults. Enrollment will target approximately half women and approximately one third African-Americans and one third Latino. 2. Ability to comply with study procedures, including directly observed dosing visits and availability and use of audio-video streaming technology. Exclusion Criteria: 1. Inability to give informed consent 2. A minimum scalp hair length of 2 cm in the occipital region. 3. Pregnancy or plan to become pregnant or unwillingness to use birth control 4. Current breastfeeding. 5. High risk of HIV-1 infection (for example: sexually active with an HIV infected partner; men who have sex with men who may engage in condom-less intercourse with HIV-infected partners or partner of unknown status during the study; males or females who exchange sex for money, shelter, or gifts; active injection drug use or during the last 12 months; newly diagnosed sexually transmitted infections in last 6 months) 6. Positive screening HIV+ ELISA or suspected acute HIV infection in the opinion of the clinician. (example signs and symptoms of acute HIV infection include combinations of fever, headache, fatigue, arthralgia, vomiting, myalgia, diarrhea, pharyngitis, rash, night sweats, and adenopathy cervical or inguinal) 7. Positive Hepatitis B (HBV) surface antigen test at screening 8. Active psychiatric illness, social condition, or alcohol/drug abuse that, in the opinion of the investigators, would interfere with study requirements. 9. History of non-traumatic, pathologic bone fractures 10. Glomerular Filtration Rate (GFR, creatinine clearance) \< 60 ml/min (MDRD equation). 11. Urine dipstick protein ≥ 2+ 12. Total bilirubin and/or hepatic transaminases (ALT and AST) ≥ 2.5x upper limit of normal 13. Absolute neutrophil count ≤ 1,500/mm3, platelets count ≤ 100,000/mm3, or hemoglobin ≤ 10 g/dL. 14. Medical condition that alters red blood cell kinetics including hemoglobinopathies or active hemolysis. 15. Any laboratory value or uncontrolled medical conditions that would interfere with the study conditions such as, heart disease and/or cancer. 16. Contraindicated concomitant medications (including investigational agents, aminoglycosides, ganciclovir/valganciclovir, chronic high-dose acyclovir/valacyclovir, cyclosporine, amphotericin B, foscarnet, and cidofovir, and products with same or similar active ingredients as the study medications (Truvada®) including ATRIPLA®, COMPLERA®, EMTRIVA®, VIREAD®; or drugs containing lamivudine or adefovir, which are close analogs of Emtricitabine (FTC) and tenofovir, respectively).