Cellular targets of infection and route of viral dissemination following an intravaginal inoculation of SIV into rhesus macaques

We used the SIV-rhesus macaque model to study the events that underlie sexual transmission of HIV-1. Four female rhesus macaques were inoculated intravaginally and atraumatically with SIVmac251, then sacrificed 2, 5, 7, and 9 days later. An in situ polymerase chain reaction technique was used to show that the first cellular targets for SIV were in the lamina propria of the vaginal and cervical mucosa, immediately subjacent to the epithelium. Phenotypic studies demonstrated that, in addition to lymphocytes, many of the infected cells were Langerhans dendritic cells. Within 2 days of inoculation, infected cells were found in the T cell regions of the draining internal iliac lymph nodes. Subsequently, systemic dissemination of SIV was rapid, as culturable virus was detectable in blood by day 5. From these results, we present a model for mucosal transmission of SIV and HIV-1.