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Bovine viral diarrhea virus (BVDV) is an important pathogen of cattle for many reasons, but partly due to the ability to suppress the bovine immune system. Numerous studies, under both natural and experimental conditions, have demonstrated the relationship between BVDV and other infectious agents, suggesting that BVDV has the ability to induce immunosuppression during primary infection in immunocompetent cattle. The specific aim of this research effort is to determine if BVDV contributes to E. coli O157:H7 carriage in cattle. This research project will examine the effect of experimental bovine viral diarrhea virus infection on the level and duration of fecal shedding of Escherichia coli O157:H7.
NON-TECHNICAL SUMMARY: Escherichia coli O157:H7 has emerged as an important public health concern, and is associated with severe disease in humans. Beef and beef products have been responsible for food borne disease outbreaks of E. coli O157:H7 in humans. This project examines the potential role of bovine viral diarrhea virus infection in Escherichia coli O157:H7 carriage in cattle. Identifying a potential on-farm risk factor for E. coli O157:H7 will assist the Alabama beef industry by identifying critical control strategies to minimize the threat of human food borne illnesses associated with E. coli O157:H7.
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APPROACH: The research objective will be assessed by comparing the level and duration of fecal E. coli O157:H7 shedding between calves undergoing an acute BVDV infection (Group A) and non-virus, sham-inoculated control calves (Group B). The detection of E. coli O157:H7 and enumeration of E. coli O157:H7 colonies will be the variable of interest in this project. Colostrum-deprived calves will be obtained, given BVDV-negative and BVDV-seronegative plasma, housed in isolation, and randomly assigned to groups. One group (Group A; n=9 calves) will receive BVDV-2 890, while the other (Group B; n=6) will receive a sham inoculation prior to both groups being inoculated with E. coli O157:H7. Calves will be examined daily, and fecal samples will be collected for culture of E. coli O157:H7 and blood samples will be collected for BVDV detection throughout the 10-week study period. The level and duration of E. coli O157:H7 shedding will be evaluated and compared between groups.