John M. Leong, M.D., Ph.D.


Lyme disease and relapsing fever bacteria of the genus Borreliae are tick-borne spirochetes that cause multisystemic infection. We have sought to investigate the spirochetal factors that promote colonization, and components of the host immune response that contribute to spirochetal clearance. We are analyzing mutants of the Lyme disease spirochete that are incapable of recognizing mammalian cell receptors to determine how pathogen-host cell interactions promote disease. We are also utilizing the highly tractable murine infection model for relapsing fever to elucidate a novel mechanism of T cell-independent immunologic memory. Upon initial attachment to intestinal epithelial cells, pathogens such as E. coli inject into host cells effector proteins that directly stimulate mammalian proteins known to control actin assembly. We are studying the action of these proteins to understand how interactions between these bacteria and the intestinal epithelium promote colonization and disease, as well as to gain insight into fundamental mechanisms of actin assembly in mammalian cells.

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