The World Health Organization estimates that 2 million people die every year from tuberculosis and that 30% of the world's population is infected. Multi-drug resistant organisms are widespread and extensively drug resistant organisms are emerging. New approaches are required to combat these virulent and drug resistant organisms (MDR/XDR TB). The proposed experiments are aimed at characterizing metabolites produced by M. tb using cholesterol as a starting material. The hypothesis is that M. tb transforms cholesterol to hormones that regulate the host immune system. The corresponding enzymatic activities that catalyze hormone synthesis represent new targets for anti-MDR-TB pharmaceutical development. The aim of this work is to identify candidate immunomodulatory metabolites produced during growth of M. tb on cholesterol and in macrophages in order to drive the identification of the genes and corresponding enzymes responsible for their formation. PUBLIC HEALTH RELEVANCE: The proposed research fits within the targeted research needs of NIAID that seeks the development of new chemotherapeutic agents against MDR/XDR TB. These experiments will provide a basis for discovering the structure of metabolites that regulate the host immune response to TB and guide development of new antibiotics that would be effective against all forms of TB including MDR/XDR TB.