Vibrio parahaemolyticus is the leading cause of seafood-related bacterial gastroenteritis in the United States. V. parahaemolyticus infection is most frequently associated with the consumption of oysters harvested from warm waters, particularly along the U.S. Gulf Coast, where vibrios grow to high levels during the summer months. The research proposed here will increase our knowledge of virulence and pathogenesis of V. parahaemolyticus O3:K6 associated with food-borne transmission. Using microbial genetics in combination with assessing V. parahaemolyticus virulence in an animal model, we will begin to understand the emergence of this pathogen and its persistence. This knowledge will allow us to begin to determine the immune parameters required to eliminate infection from the host, thus reducing food-borne illness. <P>The three specific objectives of the work are to: <ul> <LI> identify novel genes involved in V. parahaemolyticus pathogenesis<LI>evaluate V. parahaemolyticus virulence and pathogenicity by assessing the murine host response to infection<LI>quantify the expression of PGI-LysAP [a proposed virulence-enhancing protein] in wild-type and in toxRS- and rpoS-deletion mutants.
NON-TECHNICAL SUMMARY: Vibrio parahaemolyticus is a human pathogen that is the predominant cause of seafood-borne, bacterial diarrhea in the U.S. The late 1990s marked the emergence of the highly virulent pandemic V. parahaemolyticus serogroup O3:K6 clone. Two enterotoxins and two type three secretion systems (TTSSs) are present in some pathogenic isolates, but some pathogens lack these features, which indicates the presence of as yet unidentified virulence factors. We will use microbial genetics and protein characterization in combination with assessing the pathogen's virulence in an animal model. The research will increase our knowledge of virulence and pathogenicity factors in V. parahaemolyticus and provide a gateway to: determine the immune parameters required to combat, detect, and prevent infection, and to develop improved assays for V. parahaemolyticus to enhance shellfish monitoring, reduce outbreaks among shellfish consumers, and reduce impediments that outbreaks have on the industry, regulatory agencies, and other stakeholders.<P>APPROACH: To accomplish our objectives of identifying and evaluating novel genes involved pathogenesis and assessing the murine host response to infection, this study will combine genomic, proteomic, microbiological, immunological, and functional approaches to assess likely mechanisms of virulence and its modulation in V. parahaemolyticus O3:K6 and in mutants lacking a proposed virulence gene regulatory (toxRS) or a stress regulatory gene (rpoS). Our overall goal is to determine the key virulence factors required for V. parahaemolyticus pathogenicity.