A cell wall preparation of Enterococcus faecalis strain EC-12 stimulates β-defensin expression in newly hatched broiler chicks

In our previous study, a cell wall preparation of Enterococcus faecalis strain EC-12 (EC-12) prevented the colonization of vancomycin-resistant enterococci (VRE) in newly hatched broiler chicks. Relatively early prevention against VRE colonization by EC-12 administration may be related to the enhanced innate immune system. In this study we examined the effect of EC-12 on the kinetics of immunoglobulin A (IgA) concentration in the cecal digesta of chicks from 1 day to 14 days old to evaluate humoral immunity. We also examined the effect of EC-12 on β-defensin mRNA expression and lysozyme production. The IgA concentration in the cecal digesta showed a decline in chicks from 2 to 8 days old and then a recovery up to when they were 14 days old. The concentration tended to be higher in EC-12-administered chicks than in control chicks at 14 days old. EC-12 administration did not stimulate the lysozyme activities in the alimentary tract. However, β-defensin mRNA expression in the tongue and the bursa of Fabricius was higher in chicks administered EC-12 than in the control chicks at 5 days old. These results indicate that β-defensin may be one of the major defense mechanisms inhibiting VRE colonization in young chicks.