Enteropathogenic Escherichia coli (EPEC) is one of the etiological agents that causes diarrhea in weaning pigs. In this study, we report that mutating both relA and spoT genes in EPEC E2348/69 can promote bacterial clearance in porcine gastrointestinal tract (GIT). Our experimental analyses showed that an E2348/69 ΔrelAΔspoT mutant strain was not detected in porcine feces after 1 day post-infection (dpi), whereas its parental strain was continuously detected in porcine feces within 10 dpi. Histologic assessment revealed that the mutant strain was unable to induce moderate pathologic lesions in porcine GIT when compared to those with the wildtype strain. Taken together, our data suggest that the relA and spoT genes in EPEC play an important role in bacterial survival and pathogenesis in porcine GIT.

INTRODUCTION
MATERIALS AND METHODS
    Bacterial strains
    Animal challenge and fecal sampling
    Detection of E2348/69 strains in feces by PCR
    Tissue preparation and histologic assessment
RESULTS
    Mutation of the relA and spoT genes in EPEC leads torapid bacterial clearance in porcine GIT
    The double mutant of E2348/69 cannot inducepathologic lesions in pig
DISCUSSION
ACKNOWLEDGMENTS
REFERENCES

• Jun Bong Lee(College of Veterinary Medicine & Institute of Veterinary Science, Kangwon National University)
• Jang Won Yoon(College of Veterinary Medicine & Institute of Veterinary Science, Kangwon National University, The YOON Healthtech Co.,Ltd.) Corresponding Author