Establishment of a recombinant Escherichia coli-induced piglet diarrhea model.

Enterotoxigenic Escherichia coli strains induce human and animal intestinal dysfunction and injury, and cause diarrhea in weanling pigs. A recombinant E.coli strain LMG194-STa which expressed single toxin STa of ETEC was constructed by directly inserting the STa gene of ETEC into the expression vector pBAD202 and then transferring the recombinant plasmid pBAD-STa into the E.coli LMG19 host strain. Diarrhea and intestinal injury in piglets were induced by oral administration of recombinant strain LMG194-Sta. In vitro, the recombinant strain LMG194-Sta had the same toxicity to the IPEC cell as wild type strain K88, and higher toxicity than the host strain LMG194. In vivo, LMG194-STa caused severe diarrhea in piglets as K88, the diarrhea rate of LMG194-STa and K88 groups was higher than that in the LMG194 and control groups. Both K88 and LMG194-STa induced intestinal inflammation, injury, and atrophy, while adversely affecting the expression of genes for cytokines, transporters and ion channels, and nutrient metabolism. Thus, we established a porcine model of recombinant E. coli strain LMG194-STa-induced diarrhea for future nutritional and mechanistic studies of intestinal dysfunction.