Characterization of HIV Seroconverters in a TDF/FTC PrEP Study: HPTN 067/ADAPT

J Acquir Immune Defic Syndr. 2017 Jul 1;75(3):271-279. doi: 10.1097/QAI.0000000000001374.


Background: HIV Prevention Trials Network (HPTN) 067/ADAPT evaluated tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) pre-exposure prophylaxis (PrEP) in women (South Africa) and men who have sex with men (Thailand, US). Participants received once-weekly directly observed therapy (DOT) of TDF/FTC, and were then randomized to daily, time-driven, or event-driven PrEP. This report describes characterization of 12 HIV seroconversion events in this trial.

Methods: HIV rapid testing was performed at study sites. Retrospective testing included fourth generation assays, HIV RNA testing, Western blot, an HIV-1/2 discriminatory assay, resistance testing, and antiretroviral drug testing.

Results: Six of the 12 seroconverters received TDF/FTC in the DOT phase, but were not randomized (3 were acutely infected at enrollment; 2 were infected during the DOT phase; 1 was not randomized because of pregnancy). One of the 6 randomized participants had acute infection at randomization but was not diagnosed for 3-4 months because HIV rapid tests were nonreactive; continued daily PrEP use was associated with false-negative antibody tests and low HIV RNA levels. The 5 participants infected after randomization included 4 with low adherence to the PrEP regimen, and one who reported a 7-day period without dosing before infection. Three participants had TDF/FTC resistance (M184I, K65R), including 2 who received only 4 once-weekly TDF/FTC doses; most TDF/FTC mutations were detected by next generation sequencing only.

Conclusions: In HPTN 067/ADAPT, participants who acquired HIV infection had infrequent PrEP dosing or low/suboptimal adherence. Sensitive assays improved detection of HIV infection and drug resistance. Drug resistance was observed with limited PrEP exposure.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Anti-HIV Agents / therapeutic use*
  • Directly Observed Therapy*
  • Drug Resistance, Viral / drug effects*
  • Emtricitabine, Tenofovir Disoproxil Fumarate Drug Combination / therapeutic use*
  • Female
  • HIV Seropositivity / blood
  • HIV Seropositivity / drug therapy*
  • HIV Seropositivity / epidemiology
  • Humans
  • Male
  • Pre-Exposure Prophylaxis*
  • Predictive Value of Tests
  • Retrospective Studies
  • South Africa / epidemiology
  • Thailand / epidemiology


  • Anti-HIV Agents
  • Emtricitabine, Tenofovir Disoproxil Fumarate Drug Combination