IRON REGULATION & VIRULENCE--MYCOBACTERIUM TUBERCULOSIS

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The candidate is completing a three year infectious disease fellowship and has devoted the last 2 years to basic science research in tuberculosis. In particular, the candidate is interested in studying gene regulation in tuberculosis to elucidate virulence genes and protein antigens which may make important drug and vaccine targets. Through the research conducted under this grant, the candidate would like to establish herself as a junior faculty member at an academic medical institution and continue to pursue tuberculosis disease pathogenesis using molecular biologic techniques. In collaboration with Dr. John Murphy, a leader in iron-dependent regulons in diphtheria, and Dr. Richard Silver, who has developed a reproducible macrophage model of tuberculosis infection, the candidate will have the collaborative resources necessary for the successful completion of this project. The sponsor, Dr. William Bishai, has well-established expertise in mycobacterial gene regulation and tuberculosis disease pathogenesis. To complement her research, the candidate will attend approximately 3 hours per week of infectious disease and TB-related conferences. She also plans to take courses in molecular biology, tuberculosis, vaccine development, and immunology in the School of Medicine and the School of Public Health and Hygiene. Fueled by antibiotic resistance and HIV infection, the global burden of tuberculosis infection is staggering. The elucidation of virulence mechanisms and protein antigens for new antimicrobials and vaccines has moved to the forefront. Iron is an essential nutrient for the survival of most organisms and has played a central role in the virulence of multiple important infectious disease pathogens. Using the corynebacterial, iron- dependent DtxR regulon as a model, the candidate will study the mycobacterial homologue, ideR and its regulon. Preliminary results have shown that an iron-independent, corynebacterial DtxR mutant hyperrepressor attenuates Mycobacterium tuberculosis virulence in a murine model. A similar mutant of the mycobacterial ideR has been constructed and will be tested in vitro using a gel-shift assay, and in vivo in a murine and macrophage models. Taking advantage of the DtxR/IdeR "iron box", a palindromic DNA binding sequence present in all DtxR-regulated genes, other genes of interest have been identified in silico and will be examined. Elucidation of this iron-dependent IdeR regulon may lead to the identification of virulence determinants, and novel antigens for vaccines and therapeutics.