Projects include basic research to understand the relationship between healthy cattle and this human pathogen and applied research to develop effective pre-harvest interventions. Both approaches are aimed to ultimately improve the safety of our food supply. Molecular and biochemical techniques are used to relate the bacterial virulence factors and other features to its ability to persist in the ruminant gastrointestinal tract and on the farm. Microbiological and molecular genetic techniques are used to identify pre-harvest management practices that may reduce the risk of EHEC-positive cattle from entering our food chain. Development of a vaccine to prevent cattle from carrying these human pathogens is also underway. In addition, we are investigating the possibility that E. coli O157:H7 and other Shiga toxin-producing E. coli play beneficial roles in ruminant animals. To this end, we have shown that Shiga toxin, an exotoxin produced by EHEC and other non-pathogenic E. coli, has antiviral activity against bovine leukemia virus.