Doctor of Philosophy

dissertationAround 2-3 billion people worldwide are infected with Mycobacterium tuberculosis (Mtb), the bacteria that causes tuberculosis (TB). Increasing incidence of drug resistant strains of Mtb indicate a growing need for new antibiotics. Pyrrolocins A-C are a set of pyrrolodinediones isolated from an endophytic fungus (NRRL50135) from Papua New Guinea. The mechanism of action for these compounds against Mtb and other bacteria (i.e., Staphylococcus aureus) is largely unknown. We found that pyrrolocins inhibit the first committed step in fatty acid biosynthesis, a mechanism that has yet to be targeted in anti-TB therapy. Current anti-TB drug screening approaches use axenic culture to assess drug efficacy. However this does not assess efficacy against intracellular Mtb infection. In addition, cytotoxicity is determined separately. We developed a screening method in a macrophage cell line that combines infection and cytotoxicity. This screen can be used to determine effects of drug on infected cells as well as uninfected cells. TB is the leading cause of death among HIV/AIDS patients worldwide. Interactions between Mtb and HIV-infected cells have been explored. However these studies have addressed the impact on latent HIV reservoirs. We found that components of the Mtb membrane as well as bacteria co-culture resulted in HIV latency reversal. Macrophages are susceptible to Mtb and HIV infection. We explored concurrent HIV/Mtb infection in vitro. We found a small percentage of our macrophage cell line, and an even smaller percentage of our T cell line, were infected with both HIV and Mtb. Latency reversal and concurrent infection by Mtb in HIV-infected cells identify mechanisms by which Mtb may exacerbate HIV infection. These findings highlight that HIV/Mtb interactions should be considered during anti-HIV and anti-TB drug therapy development as they will likely be implemented in HIV/TB patients. The findings in this work collectively provide new strategies to treat TB and HIV, whether that is offering an alternative to current antibiotics with a novel mechanism, assessing drug efficacy using an in vitro screening method that models intracellular Mtb, or understanding processes (i.e., latency reversal and concurrent infection) that may occur in HIV/TB coinfected patients which could have ultimate consequences on therapeutic efficacy in these patients