<OL> <LI> Develop an in vitro model system for the binding of E. coli O157:H7 to bovine recto-anal junction tissue. <LI>Characterize the binding of E. coli O157:H7 to the bovine recto-anal junction. <LI>Characterize the shedding patterns of E. coli O157:H7 with different tir alleles in cattle colonized at the recto-anal junction.
Approach: Colons will be obtained from commercial beef processing plants to determine the specific bind of E. coli O157:H7 to the RAJ and then determine the mechanism of binding, whether virulence factors are related to binding, and whether non-pathogenic bacteria inhibit binding. We will determine whether different tir alleles result in different colonization of the RAJ and affect persistence of shedding.