CCTG 595: Text Messaging Intervention to Improve Adherence to PrEP in High-risk MSM

Inclusion Criteria: * Man or transgender M to F who has sex with men. * Age 18 years or older. * Subjects must have substantial ongoing risk of acquisition of HIV as evident by one or more of the following: * Has at least one HIV infected sexual partner for ≥4 weeks. * No condom use during anal intercourse with ≥3 male sex partners who are HIV-positive or of unknown HIV status during the last 3 months. * No condom use during anal sex with ≥1 male partner and STI diagnosis during the last 3 months. * Negative for HIV infection by rapid HIV test and confirmed negative by NAT or other sensitive method such as antibody- antigen test. * Acceptable laboratory values in the past 30 days: * Calculated creatinine clearance of at least 60 mL/min by the Cockcroft-Gault formula (eCcr (male) in mL/min = \[(140 - age in years) x (lean body weight in kg)\] / (72 x serum creatinine in mg/dL) * Alanine aminotransferase (ALT) and/ or aspartate aminotransferase (AST) \< 3 x upper limit of normal (ULN) * Hemoglobin \> 9 g/dL * Absolute neutrophil count \> 750/ mm3 * Platelets \> 75,000/ mm3 Exclusion Criteria: * Unable to give informed consent. * Active hepatitis B (positive hepatitis B surface antigen (HBSAg) or HBSAg negative/ HB core antibody positive/ HBV PCR positive). * Has substantial medical condition, that in the opinion of the investigator would preclude participation, as defined by * cardiovascular condition that may lead to an increased risk of complication if placed on study drugs. * gastrointestinal condition that would impair absorption of study drugs. * neurological or psychiatric condition that would significantly impair the ability to adhere to PrEP. * calculated GFR \< 60 mL/min. * alcohol or drug abuse or dependence that would significantly impair the ability to adhere to PrEP (only for those with severe impairment). * other medical condition that would unacceptably increase the risk of harm from study drug or significantly impair the ability to adhere to PrEP. * Suspected sensitivity or allergy to the study drug or any of its components. * Currently using an essential product or medication that interacts with the study drug such as the following: * ART (including nucleoside analogs, non-nucleoside reverse transcriptase inhibitors, protease inhibitors or investigational antiretroviral agents) * Agents with known nephrotoxic potential: * aminoglycoside antibiotics (including gentamicin) * IV amphotericin B * cidofovir * cisplatin * foscarnet * IV pentamidine * IV vancomycin * oral or IV gancyclovir * other agents with significant nephrotoxic potential * Drugs that slow renal excretion * Probenecid * Immune system modulators * Systemic chemotherapeutic agents (i.e. cancer treatment medications) * Ongoing systemic corticosteroids (with the exception of short courses of tapering steroid doses for asthma or other self- limited condition). * Interleukin-2 (IL-2) * Interferon (alpha, beta, or gamma) * Other agent known to have a significant interaction with TDF or FTC * Proteinuria 2+ or greater by urine dipstick * Signs or symptoms suggestive of acute HIV infection * Any other reason or condition that in the opinion of the investigator would interfere with participation, complicate interpretation of study outcome data, or otherwise interfere with achieving the study objectives.