Are Virulent Strain-Specific DNA Sequences of Vibrio vulnificus Essential for Virulence?

Vibrio vulnificus is the leading cause of death in the U.S. associated with consumption of shellfish. The rapid and lethal disease that can follow consumption of contaminated oysters has had immense negative impact on the industry as well as consumer attidues and practices. However, not all strains of V. vulnificus have the potential to cause disease; there arevirulent and avirulent strains in the environment. Currently there is no practical test to determine if seafood products contain hazardous versus avirulent strains of V. vulnificus In currently funded USDA research, we are using genetic methods to identify DNA sequences that are unique to the virulent versus avirulent strains. These virulent strain-specific sequences could be used to screen oysters and harvested waters for the presence of V. vulnificus strains with the potential to cause human disease. We propose to examine the relationship of virulent strain-specific DNA sequences to the disease process by determining if genes encoded on virulent strain-specific genomic sequences are essential for virulence, or if they are not only markers for virulence by coincidence. Determining the functional importance of DNA sequences unique to virulent strains will add credibility to the use of these new tools to accurately screen for virulent versus avirulent strains. By identifying virulence genes, we will contribute to the understanding how this devastating food-borne pathogen can kill humans so rapidly after consumption of contaminated sea food. This information could be integrated into CDC, FDA, and State efforts to determine the epidemiology of infections and to develop interventions to reduce risk of V. vulnificus disease.