Seminal exosomes and HIV-1 transmission

Exosomes are endosomal-derived membrane-confined nanovesicles secreted by many (if not all) cell types and isolated from every human bodily fluid examined up to now including plasma, semen, vaginal secretions and breast milk. Exosomes are thought to represent a new player in cell-to-cell communication pathways and immune regulation, and be involved in many physiological and pathological processes. Susceptibility to HIV-1 infection can be impacted by exosomes, while HIV-1 pathogenesis can alter exosomal function and composition. Exosomes isolated from semen and vaginal fluid of healthy individuals can inhibit HIV-1 infection and/or potently block viral transfer in vitro. However, the role of exosomes in HIV-1 transmission and progression is not fully understood yet and some studies show conflicting results, mainly for exosomes isolated from plasma and breast milk. Determining the composition of exosomes from infected donors and studying their interaction with HIV-1 in vitro compared to exosomes isolated from uninfected donors will provide insights into the role exosomes play in HIV-1 transmission during sexual intercourse and breastfeeding.