The overall objective of this research is to understand the role that human female reproductive tract (FRT) epithelial cells play in innate immune protection against HIV-1. As sentinels of innate immune defense, epithelial cells throughout the reproductive tract are the first line of protection against sexually transmitted infections and are crucial for orchestrating a rapid response to potential viral pathogens. Our goal in this proposal is to test the hypothesis that epithelial cells from White-American, African- American, and Tanzanian women exhibit intracellular and secreted antiviral activity that protects the reproductive tract against HIV-1. The specific aims of the current research project are to answer the following questions: 1) To what extent do epithelial cell secretions protect the female reproductive tract from HIV-1? 2) Do intracellular antiviral factors inhibit HIV-1 replication? 3) To what extent do candidate topical microbicides affect epithelial cell innate defenses? 4) Do epithelial cells influence the risk of HIV-1 infection of T cells and macrophages in the underlying stromal FRT? 5) Do FRT epithelial cells from Tanzanian women exhibit secreted and/or intracellular mechanisms of protection against HIV-1? We plan to investigate these questions using human primary epithelial cells from throughout the female reproductive tract and reproductive tract cell lines, since these cells are infectable by HIV-1, capable of protecting against HIV-1 infection, and responsive to sex hormones. The research described in this proposal will further our understanding of the mucosal immune responses involved in defending against HIV-1 and should lead to the identification of ways to augment protective responses. These studies should provide the basis of knowledge essential for the development of more effective microbicides and therapeutic interventions.