Semen Extracellular Vesicles From HIV-1-Infected Individuals Inhibit HIV-1 Replication In Vitro, and Extracellular Vesicles Carry Antiretroviral Drugs In Vivo

Background: Extracellular vesicles (EVs) are cell-derived vesicles with diverse functions in intercellular communication including disease and infection, and EVs seem to influence HIV-1 pathogenesis. EVs isolated from HIV-1-uninfected semen (SE), but not blood (BE), contain factors that interfere with HIV-1 infection and replication in target cells. The reason for this dichotomy is unknown. Furthermore, the effect of HIV-1 infection and antiretroviral (ARV) drugs on the anti-HIV-1 effects of SE and BE is unknown. Here, we characterize EVs and EV-free plasma isolated from HIV-infected donor semen and blood and their effects on HIV infection. Methods: EVs and EV-free plasma were purified from autologous blood and semen of HIV-negative, HIV-infected antiretroviral therapy (ART)-naive, and HIV-infected ART-treated participants. HIV infection was assessed in a TZM-bl cell reporter system. ARV concentrations were analyzed using liquid chromatography-mass spectrometry. Results: SE isolated from both HIV-negative and HIV-infected, ART-naive donors inhibited HIV-1 infection, but BE and semen and blood EV-free plasma did not. By contrast, BE, SE, and EV-free plasma from HIV-infected, ART-treated donors inhibited HIV-1. Importantly, exosomes isolated from ART-treated donors contained concentrations of ARV drugs (ART-EVs) at biologically relevant inhibitory levels. Conclusions: The HIV-1-inhibitory phenotype of SE is independent of donor HIV-1 or ART status, and ARV drugs and their metabolites are SE- and BE-associated in vivo.