Effects of a novel Lactobacillus amylovorus-like strain on pathogenic prevalence and host-response in piglets challenged with enterotoxigenic Escherichia coli K88

Previous studies have shown that strains closely related to Lactobacillus amylovorus are widely distributed as common porcine intestinal commensals. Phenotypic and molecular taxonomic characterizations, however, have revealed significant differences with the nearest type strains. Here we examined the protective effect of a porcine commensal isolate, L. amylovorus-like strain 001 (LA1), against enterotoxigenic Escherichia coli K88 (ETEC) challenge in vivo. Piglets (n=48) were subjected to one of two dietary treatments, a control diet and a diet containing LA1, and experimentally infected with ETEC. As revealed by a newly developed strain-specific real-time PCR assay the LA1 persistence was accompanied by a significant reduction of ETEC prevalence in the porcine ilea samples. Furthermore, to determine to what extent the piglet immune system was stimulated by the administered LA1, the concentration of total secretory IgA (sIgA) was determined in porcine intestinal jejunal secrete, blood serum and saliva. Total sIgA contents in jejunum secrete and blood serum was not significantly affected by the LA1 supplementation. In contrast, total amount of sIgA in saliva was comparable to the level before the ETEC challenge in the piglets fed LA1, while the sIgA amount decreased significantly in the control group (р<0.05). Moreover, an improved daily weight gain (+ 74%, P<0.05) was also observed in the piglets that received LA1. Together, the data indicate that L. amylovorus-like strain 001 exerts a protective effect against the ETEC infection while improving the weight gain and immunity of weaning piglets.