Submitted to: Infection and Immunity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/29/1999
Publication Date: N/A
Citation: Interpretive Summary: Cattle are important reservoirs of Escherichia coli O157:H7 and other enterohemorrhagic E. coli (EHEC) foodborne pathogens that cause severe diarrhea and sometimes kidney failure and death in humans. Our goal is to develop a vaccine that prevents EHEC O157:H7 infections in cattle and thus reduces human infections. We need an animal model to test EHEC vaccines. Colostrum-deprived (CD) neonatal piglets are a useful model for studying Escherichia coli O157:H7 infections. Our objective was to determine if colostrum-fed (suckling) piglets are susceptible to EHEC O157:H7 infection and can be used to test EHEC vaccines. We inoculated 30 suckling piglets from three litters with EHEC O157:H7. All developed severe nervous system disease within 24 to 36 h after they were inoculated. This showed that suckling piglets are susceptible to EHEC disease. Pregnant sows will be vaccinated against EHEC O157:H7 to determine if suckling piglets that ingest maternal antibodies from vaccinated pigs are protected from experimental EHEC disease. The suckling piglet EHEC infection model will be useful for identifying vaccines that can interfere with EHEC infections. Such vaccines could reduce O157:H7 levels in cattle and thus reduce EHEC infections in humans.
Technical Abstract: Colostrum-deprived (CD) neonatal piglets are useful models for studying enterohemorrhagic E. coli (EHEC) pathogenesis. The objective of this study was to determine if neonatal suckling piglets, like CD neonatal piglets, are susceptible to EHEC O157:H7 colonization and disease. If so, we can use suckling piglets in passive immunization studies to determine if intimin-based vaccines can protect neonatal piglets from experimental EHEC O157:H7 disease. To our surprise, EHEC O157:H7 strain 86-24 caused severe neurological disease in a greater proportion of neonatal suckling piglets (30 of 30) than CD piglets (3 of 5). Neurological signs appeared earlier in suckling piglets (< 24 h PI) than in CD piglets (greater than or equal to 42 h PI), and brain lesions were more common and more severe in suckling piglets. EHEC 86-24 caused attaching and effacing (A/E) lesions in all suckling and CD piglets. Shiga toxin-negative O157:H7 strain 87-23 caused no neurological disease but did colonize and produce A/E lesions in suckling piglets. Because the Shiga toxin- positive EHEC caused such rapid and severe systemic disease in suckling piglets, it will be more humane to use a nontoxigenic, intimin-producing O157:H7 strain for testing the efficacy of intimin vaccines.