Abstract
Enterotoxigenic Escherichia coli (ETEC) is a major cause of post-weaning diarrhea (PWD) in pigs and causes significant damage to the swine industry worldwide. In recent years, there has been increased regulation against the use of antibacterial agents in swine due to their health risks. Utilizing experimental models that consistently recapitulate PWD is important for the development of non-antibacterial agents against PWD in pigs. In this study, we established a highly reproducible PWD infection model by examining differences in adhesion of ETEC to the intestinal tissue as well as the association between MUC4 polymorphisms and sensitivity to PWD. Post-weaning diarrhea differences between pig breeds were also examined. The adhesion to enterocytes varied from 104.0 to 106.4 CFU/mL even among the F4 ETEC strains. Experimental infection revealed that PWD can be induced in all MUC4 genotypes after infection with 1010 CFU/pig of highly adherent ETEC, although there were variable sensitivities between the genotypes. Lowly adherent ETEC did not cause PWD as efficiently as did highly adherent ETEC. The incidence of PWD was confirmed for all pigs with the ETEC-susceptible MUC4 genotypes in all of the breeds. These results indicate that high-precision and reproducible experimental infection is possible regardless of pig breeds by controlling factors on the pig-end (MUC4 genotype) and the bacterial-end (adhesion ability).
Highlights
Post-weaning diarrhea (PWD) is most often caused by enterotoxigenic Escherichia coli (ETEC)in piglets 3–10 days after weaning
ETEC-susceptible MUC4 genotypes in all of the breeds. These results indicate that high-precision and reproducible experimental infection is possible regardless of pig breeds by controlling factors on the pig-end (MUC4 genotype) and the bacterial-end
Many E. coli strains isolated from pigs express F4 as an adhesion gene, which is consistent with the present result [18,19,20]
Summary
Post-weaning diarrhea (PWD) is most often caused by enterotoxigenic Escherichia coli (ETEC). Pigs infected with ETEC typically exhibit watery diarrhea lasting one to five days, causing death by dehydration or growth deterioration in the surviving piglets and resulting in serious economic loss in the swine industry worldwide [1,2]. Enterotoxigenic E. coli that induces PWD produces heat-labile enterotoxin (LT) and/or heat-stable enterotoxin (STa and STb) and have fimbriae required to colonize intestinal cells. Enterotoxigenic E. coli exhibits mainly F4 and F18 fimbriae in pigs. F5, F6 and F41 fimbriae have been reported, their separation frequency.
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