Submitted to: ARS Food Safety and Inspection Service Research Workshop
Publication Type: Abstract Only
Publication Acceptance Date: 12/3/1998
Publication Date: N/A
Technical Abstract: Cattle are a source of E. coli O157:H7 and other Shiga toxin-producing E. coli (STEC) which cause foodborne disease including bloody diarrhea, severe kidney disease, and sometimes death. Identifying the site and mechanism of E. coli O157:H7 adherence and colonization in cattle is a first step in developing intervention strategies, such as vaccines, to reduce the amount of O157:H7 in the intestinal tract and feces. This should decrease the incidence of human disease caused by the consumption of contaminated beef. Effective vaccines against other types of E. coli that cause diarrhea in animals have been developed based on an immune response to specific bacterial antigens required for colonization. We believe that an immune response to O157:H7 antigens required for colonization may be effective in reducing the amount of O157:H7 in cattle. We have developed reproducible experimental models of O157:H7 infection in cattle (neonatal and weaned). The models are a necessary prerequisite for determining the efficacy of any vaccine or other treatment to reduce O157:H7 shedding. We are using these models to characterize the role of specific bacterial genes in colonization and pathogenesis of STEC in cattle. We have found that intimin, the product of the eaeA gene, is required for colonization in neonatal and weaned calves. This suggests that intimin could be used as an effective immunogen to prevent O157:H7 colonization and reduce bacterial shedding in feces. We are testing the hypothesis that anti-intimin vaccines may reduce the prevalence of O157:H7 infections in cattle and thus reduce the risk of O157:H7 disease in humans.