Preexposure Prophylaxis with Tenofovir or Emtricitabine-Tenofovir Reduces Herpes Simplex Virus Type -2 Transmission

Pre-exposure prophylaxis with the oral antiretrovirals tenofovir or emtricitabine combined with tenofovir has been shown to reduce the risk of HIV infection significantly in several randomized controlled clinical trials.¹

Because of suggested activity against Herpes Simplex Virus type 2(HSV-2) in vitro,² a recent study was designed to examine the efficacy of daily world pre-exposure prophylaxis regimens with tenofovir or emtricitabine-tenofovir in reducing the acquisition of HSV-2.

As reported in the Annals of Internal Medicine, a secondary analysis from a randomized placebo-controlled trial conducted in 9 research sites in Kenya and Uganda was conducted.³ The investigators examined HSV-2 seroconversion rates in the study population. They identified 131 participants who had incident HSV-2 infections with an incidence of 5.64 per 100 person–years in the pre-exposure prophylaxis group and 7.7 per 100 person–years in the placebo group. Pre-exposure prophylaxis was associated with a hazard ratio for HSV-2 acquisition of .70 (95% confidence interval, 0.49 to 0.99; P =0.047).³

The investigators concluded that pre-exposure prophylaxis with oral tenofovir-based regimens reduced HSV-2 acquisition by 30% compared with placebo in subjects who were initially HSV-2 seronegative.

This study has some limitations including its inability to detect and exclude individuals with acute HSV-2 infection at the beginning of the study due to the unavailability of laboratory methods. Also, the study is a secondary analysis of the clinical trial that was not originally designed to test the efficacy of tenofovir for preventing HSV-2 seroconversion.³Key Point: HSV-2 is highly prevalent in HIV-1-infected patients and is a significant risk factor for HIV-1 acquisition. This study demonstrates an added benefit to tenofovir- based preexposure prophylaxis regimens in preventing HSV-2.
 

References:

1. Grant RM, Lama JR, Anderson PL, et al, iPrEx Study Team. Preexposure chemoprophylaxis for HIV prevention in men who have sex with men. N Engl J Med. 2010; 363:2587-2599.
2.Balzarini J, Holy A, Jindrich J, et al. Differential antiherpesvirus and antiretrovirus effects of the (S) and (R) enantiomers of acyclic nucleoside phosphonates: potent and selective in vitro and in vivo antiretrovirus activities of (R)-9-(2-phosphonomethoxypropyl)-2,6-diaminopurine. Antimicrob Agents Chemother. 1993; 37:332-338.
3. Celum C, Morrow RA, Donnell D, et al, for the Partners PrEP Study Team. Daily oral tenofovir and emtricitabine–tenofovir preexposure prophylaxis reduces Herpes Simplex Virus Type 2 acquisition among heterosexual HIV-1–uninfected men and women: a subgroup analysis of a randomized trial. Ann Intern Med. 2014;161:11-19.