Persistent Colonization by E. coli O157:H7 in Ruminants

Escherichia coli 0157:H7 and other Shiga toxin-producing E. coli (STEC) cause acute gastrointestinal illness in people. The majority of human disease is associated with the consumption of contaminated foods, many of which originate from cattle. The principal problem appears to be that STEC become established in the intestinal tract of mature cattle or sheep, which then serve as a reservoir. The long-term goal of the proposed research is to eliminate cattle and sheep as a reservoir of STEC. The central hypothesis is that virulence factors produced by STEC confer an advantage to the organism that allows for the development of an asymptomatic carrier-shedder state. In preliminary studies, the investigator has developed a sheep model for the carrier-shedder state of E. coli O157:H7. This model will be used to complete two objectives to test the hypothesis: 1) Determine if intimin (a bacterial protein required for one type of attachment in the intestine) is required for E. coli O157:H7 to establish a persistent population in mature sheep. 2) Determine if Shiga toxin increases the population of E. coli O157:H7 in mature sheep. This research will benefit US agriculture by determining if either intimin or Shiga toxin should be further investigated as a potential vaccine candidate to eliminate E. coli O157: H7 from cattle and sheep.