This project addresses two major areas relevant to microbial pathogenicity, risk assessment and methods development. First, data will be provided on the virulence factors that have an impact on the risk associated with Salmonella or Vibrio infection. Specifically, virulence factors will be identified, characterized and studied in tissue culture and animal models. Animal models will be used to determine dose response data. Second, rapid methods of detecting microbial pathogens in foods based on detection of virulence genes or proteins will be developed. Once biosensor/microarray technology is available, methods will be adapted to this system.
Assessing the risks associated with pathogenic microorganisms and developing effective methods for their detection and control are dependent on having detailed knowledge about the factors that contribute to their virulence.Some virulence determinants of Salmonella and Vibrio species are unknown or poorly characterized. Work on this project includes : Characterizing virulence determinants; Developing detection systems based on sequences of genes encoding virulence factors; Studying the effects of virulence factors in animal models; Using animal models to collect dose response data. Bacterial strains from foodborne outbreaks will be characterized using in vitro and in vivo virulence assays. Those strains that have novel virulence factors will be studied in depth. Virulence factors (primarily toxins, pili and proteases) will be purified by standard protein chemistry methods. When N-terminal sequences have been determined, the virulence gene will be cloned. Primers for virulence genes will be selected and assays developed for the gene. The virulence of strains with and without the specific virulence factor will be tested in animal models. Dose response data will be generated. When available, detection systems will be coupled with biosenor technology.
Detection methods will be developed. Dose response data for science-based risk assessments will be generated and evaluated. CFSAN will gain science-based information on which to base regulations and industry guidelines.