Combination Emtricitabine and Tenofovir Disoproxil Fumarate Prevents Vaginal Simian/Human Immunodeficiency Virus Infection in Macaques Harboring Chlamydia trachomatis and Trichomonas vaginalis

Genital inflammation associated with sexually transmitted infections increases susceptibility to human immunodeficiency virus (HIV), but it is unclear whether the increased risk can reduce the efficacy of pre-exposure prophylaxis (PrEP). We investigated whether coinfection of macaques with Chlamydia trachomatis and Trichomonas vaginalis decreases the prophylactic efficacy of oral emtricitabine (FTC)/tenofovir disoproxil fumarate (TDF). Macaques were exposed to simian/human immunodeficiency virus (SHIV) vaginally each week for up to 16 weeks and received placebo or FTC/TDF pericoitally. All animals in the placebo group were infected with SHIV, while 4 of 6 PrEP recipients remained uninfected (P= .03). Oral FTC/TDF maintains efficacy in a macaque model of sexually transmitted coinfection, although the infection of 2 macaques signals a modest loss of PrEP activity.