The Cellular Pharmacology of F-TAF in Dried Blood Spots

Inclusion Criteria: 1. Ambulatory 18-59 year old adults. Enrollment will proceed without the need to meet specific race/gender targets, but balanced gender and African-Americans and Latino representation will be sought. 2. Ability to comply with study procedures, including directly observed dosing visits and availability and use of video streaming technology. Exclusion Criteria: 1. Inability to give informed consent 2. Pregnancy or plan to become pregnant in the next 12 months or unwillingness to use birth control 3. Current breastfeeding 4. 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 condomless intercourse with HIVinfected 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 5. 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) 6. Positive Hepatitis B Virus (HBV) surface antigen test at screening 7. Active psychiatric illness, social condition, or alcohol/drug abuse that, in the opinion of the investigators, would interfere with study requirements. 8. Glomerular Filtration Rate (GFR) estimate \< 60 ml/min (MDRD equation). 9. Urine dipstick protein ≥ 2+ 10. Total bilirubin and/or hepatic transaminases (ALT and AST) ≥ 2.5x upper limit of normal 11. Absolute neutrophil count ≤ 1,500/mm3, platelets count ≤ 100,000/mm3, or hemoglobin ≤ 10 g/dL. 12. Symptomatic hemoglobinopathies or active hemolysis. 13. History of pathological, non-traumatic bone fractures 14. Any laboratory value or uncontrolled medical conditions that, in the opinion of the investigators, would interfere with the study conditions such as, heart disease and/or cancer. 15. Prohibited concomitant medications are: * investigational agents (within 30 days of enrollment), * aminoglycosides, * ganciclovir/valganciclovir, * chronic high-dose acyclovir/valacyclovir (\>800mg acyclovir or \> 500mg valacyclovir for 7 days), * cyclosporine, amphotericin B, foscarnet, and cidofovir, and products with same or similar active ingredients as the study medications including TRUVADA®, ATRIPLA®, COMPLERA®, EMTRIVA®, VIREAD®; or drugs containing lamivudine or adefovir, which are close analogs of FTC and tenofovir, respectively.