Mycoplasma genitalium is a sexually transmitted pathogen that infects epithelial cells of the male and female reproductive tracts. This agent causes intense inflammation in these tissues, and infections can be long-lasting. Genital-mucosal transmission of HIV-1 (HIV) occurs most efficiently in inflamed tissues because of the presence of inflammatory cytokines and other mediators that promote infection of HIV to target cells. A long term objective of this proposal is to understand the relationship between M. genitalium infection and HIV dissemination/transmission. We propose here to use a dual-chamber Transwell coculturing format to model the genital-mucosal microenvironment, with a confluent epithelial cell monolayer (uninfected or infected with M. genitalium) in the top chamber, over a semipermeable membrane, and lymphoid cells representing those of the cervical-vaginal mucosae in the bottom chamber. Using this system, we plan to determine (a) whether stepped doses of M. genitalium infection of the mucosal epithelial cells facilitate dose-dependent HIV movement across the epithelial barrier;(b) whether stepped doses of M. genitalium-infected cells promote dose- dependent noninfectious HIV capture by dendritic cells (DCs) in the bottom well, and (c) whether stepped doses of M. genitalium-infected cells amplify the extent to which these DCs transfer their captured HIV, in an infectious form and in a dose-dependent fashion, to target CD4+ T cells co-cultured with them in the bottom well. This study will be the first to ask directly whether and how local M. genitalium infection amplifies an important mucosal HIV transmission event. If M. genitalium proves to be a potent facilitator of HIV infection in this system, this will have clear implications for prevention of HIV sexual transmission. In the public health context, screening for M. genitalium infection, and effective treatment of infections, may significantly slow HIV spread in populations at risk. PUBLIC HEALTH RELEVANCE: Mycoplasma genitalium is a common bacterium that causes sexually transmitted diseases such as cervicitis in women and urethritis in men. In both sexes, the bacterium infects mucosal epithelial cells. It has been speculated that susceptibility to sexual HIV transmission is increased in women whose cervical epithelial cells are infected by M. genitalium. We therefore propose to determine whether M. genitalium infection of cultured epithelial cells can promote HIV infection of T cells cocultured with them. This study will be the first to ask whether M. genitalium infection promotes HIV transmission. If it does, then effective screening and treatment for M. genitalium may slow HIV spread in populations at risk.