Diarrheal disease caused by enteric bacteria has been universally established as an important endemic health threat and a major source of food borne disease. Over 76 million cases and 5,000 deaths result from food borne illness in the Unites States annually. <P> Enterohemorrhagic E. coli (EHEC) is especially important because it is the leading cause of pediatric renal failure and is commonly transmitted via contaminated meat and vegetable products. In spite of the appreciated magnitude of the threat to human health caused by EHEC, we still do not fully understand how EHEC causes diarrhea by disrupting the normal cellular functions of the host intestine. <P> The central hypothesis for the proposed research is that NleF contributes to EHEC virulence by subverting the function of the host Tmp21 (p23) protein, an important component of intracellular protein transport vesicles. The specific aims of this project are to 1) map the NleF/Tmp21 binding interface and 2) characterize the influence of NleF on host protein trafficking.<P> This project will be significant because it will characterize how the EHEC virulence factor NleF interacts with the host protein transport machinery. These studies are expected to have a significant positive impact on the design of new strategies to combat diarrheal pathogens. <P> PUBLIC HEALTH RELEVANCE: E. coli is a significant source of food borne disease caused by ingestion of under-cooked beef products or contaminated vegetables. An E. coli protein has been discovered that may contribute to diarrheal disease by altering the function of mammalian intracellular protein transport machinery. The applicant is characterizing the biological activity of this protein with the goal of developing new therapeutic strategies for E. coli and related diarrheal pathogens.