Norethisterone Enanthate Increases Mouse Susceptibility to Genital Infection with Herpes Simplex Virus Type 2 and HIV Type 1

Norethisterone enanthate (NET-EN) and depot-medroxyprogesterone acetate (DMPA) are two forms of injectable progestin used for contraception. Whereas clinical research indicates that women using DMPA are more susceptible to HIV and other genital pathogens, causal relationships have not been determined. Providing an underlying mechanism for this connection, however, is recent work that showed DMPA weakens genital mucosal barrier function in mice and humans and respectively promotes susceptibility of wild-type and humanized mice to genital infection with HSV type 2 and HIV type 1. However, analogous effects of NET-EN treatment on antivirus immunity and host susceptibility to genital infection are much less explored. In this study, we show that compared with mice in estrus, treatment of mice with DMPA or NET-EN significantly decreased genital levels of the cell–cell adhesion molecule desmoglein-1 and increased genital mucosal permeability. These effects, however, were more pronounced in DMPA- versus NET-EN–treated mice. Likewise, we detected comparable mortality rates in DMPA- and NET-EN–treated wild-type and humanized mice after intravaginal infection with HSV type 2 or cell-associated HIV type 1, respectively, but NET-EN treatment was associated with slower onset of HSV-induced genital pathology and lower burden of systemic HIV disease. These findings reveal DMPA and NET-EN treatment of mice significantly reduces genital desmoglein-1 levels and increases genital mucosal permeability and susceptibility to genital pathogens while also implying that NET-EN generates less compromise of genital mucosal barrier function than DMPA.