My research interests are the molecular pathogenesis of bacterial disease, in particular Vibrio vulnificus, and detection of infectious agents for biodefense.
V. vulnificus infection is noted for the extensive tissue damage that occurs after ingestion of vibrios in raw oysters or contamination of wounds. V. vulnificus avoids phagocytosis, replicates extensively in the interstitial fluid, and then causes damage, most likely by the secretion of a plethora of extracellular factors. We are focusing our studies on how the vibrios replicate so rapidly, how they avoid the host defenses, and how they cause damage in such a short period of time, 24 hours after infection. We developed a mouse model which reproduces the important characteristics of human disease, including predisposing conditions and tissue damage. We have used this model to perform comparative analysis of numerous V. vulnificus strains of both clinical and environmental origin. We are using molecular genetic tools, including signature-tagged mutagenesis and alkaline phosphatase fusion/insertion mutagenesis, to identify virulence genes using this animal model. Additionally, we have developed a marker plasmid tool to enable the differentiation of growth versus death of different vibrio strains or mutants in the animal host. We are now moving into genome-wide analysis of gene expression to determine the transcriptome of V. vulnificus growing in infected host tissues compared with growth in vitro.
In biodefense, we are collaborating with researchers at the University of South Florida to develop immunological tools for use in a real time/near real time, fiber optic-based system to detect bacterial and viral agents of bioterrorism. We are producing recombinant phage display scFv antibodies which can be genetically manipulated for optimal use in such systems. For example, antigen-binding sequences are genetically fused with biotinylation cassettes to enable efficient biotinylation of the scFv proteins by specialized E. coli strains. Other reporter fusions constructions are being considered. Because efficient coating of detection substrates (plastic) is not efficient, we are developing hybrid detection reagents that specifically bind to polystyrene and the chosen antigen to improve efficiency of capturing target antigens. Infectious agents currently under investigation include Vibrio cholerae, E. coli O157:H7, Listeria monocytogenes, Salmonella enterica serovar Typhimurium, and Vaccinia virus (as a surrogate for Variola).
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