Researcher Resources Member Profiles John Leong, Ph.D., M.D.
John Leong, Ph.D., M.D.
Professor, University of Massachusetts Medical School
Faculty Appointment(s) In: Molecular Genetics and Microbiology
Other Affiliation(s): Bacterial Genetics and Pathogenesis, Cell Dynamics Group, Center for AIDS Research, Graduate School of Biomedical Sciences, Immunology and Virology, Interdisciplinary Graduate Program
S6, Rm 214
364 Plantation Street
Worcester, Massachusetts 01605
Phone: 508-856-4059
E-mail:
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Research Interests
Interactions of pathogenic bacteria with mammalian cells.
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.
Enteropathogenic and enterohemorrhagic Escherichia coli O157:H7 are important intestinal pathogens that stimulate actin polymerization in the host cell directly beneath the bound bacterium. Upon initial attachment to intestinal epithelial cells, these pathogens 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.