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P3.370 Daily Oral Emtricitabine/Tenofovir Pre-Exposure Prophylaxis and Prevention of HSV-2 Acquisition Among Heterosexual Men and Women
  1. C Celum1,
  2. R Morrow2,
  3. D Donnell2,
  4. T Hong1,
  5. K Thomas1,
  6. K Fife3,
  7. E Nakku-Joloba4,
  8. A Mujugira1,
  9. J Baeten1
  1. 1University of Washington, Seattle, WA, United States
  2. 2Fred Hutchinson Cancer Research Center, Seattle, WA, United States
  3. 3Indiana University, Indianapolis, IN, United States
  4. 4Makerere University, Kampala, Uganda

Abstract

Background Daily oral and pericoital tenofovir-based antiretroviral pre-exposure prophlyaxis (PrEP), reduced risk of HIV-1 acquisition in trials among high risk populations; oral emtricitabine(FTC)/tenofovir (TDF) received a label indication for HIV-1 prevention. Peri-coital dosing of 1% tenofovir gel also reduced the risk of acquisition of herpes simplex virus type 2 (HSV-2), by 51%. Tenofovir has anti-HSV-2 activity in vitro, although the EC90 is high. We conducted a randomised, placebo-controlled trial of daily oral TDF and FTC/TDF as PrEP among 4747 HIV-1 uninfected partners in of heterosexual serodiscordant partnerships from Kenya and Uganda (the Partners PrEP Study) and demonstrated FTC/TDF reduced HIV-1 acquisition by 75%. We performed a secondary analysis of HSV-2 acquisition among initially HSV-2 seronegative participants.

Methods We tested archived sera from baseline for HSV-2 by EIA (Focus) and HSV-2 Western blot. Among initially HSV-2 seronegative participants, HSV-2 seroconversion was assessed at the last study visit prior to unblinding the placebo arm in July 2011.

Results 528 participants on FTC/TDF (35%) and 481 participants on placebo (32%) were HSV-2 seronegative at baseline. Eighty-nine post-randomization HSV-2 seroconversions were observed: 37 among those assigned FTC/TDF (incidence 4.4/100 person-years) and 52 among those assigned placebo (incidence 6.6/100 person-years). Compared to placebo, FTC/TDF reduced HSV-2 acquisition by 35% (95% CI 1 to 58, p = 0.05). Anti-HSV-2 effects trended towards protection for both men and women. Case-cohort analysis of plasma tenofovir levels to determine efficacy by drug exposure and subgroup analysis by HSV-2 status of the HIV-1 infected partner are underway.

Conclusions Among African heterosexual men and women, daily oral FTC/TDF PrEP modestly reduced the risk of HSV-2 infection in the context of a study population with high adherence and for whom high efficacy against HIV-1 acquisition was demonstrated. Potential protection against HSV-2 in addition to HIV-1 could increase the public health benefits of PrEP.

  • HSV-2
  • PrEP
  • Serodiscordant

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