High dose and low dose Lactobacillus acidophilus exerted differential immune modulating effects on T cell immune responses induced by an oral human rotavirus vaccine in gnotobiotic pigs

► Dose effects of lactobacilli on T cell responses to rotavirus vaccine were studied. ► Low dose promoted Th1 and down-regulated Treg cell responses in gnotobiotic pigs. ► High dose increased natural and induced Treg cells and their TGF-β/IL-10 production. ► Dose effects were similar in the intestinal and systemic lymphoid tissues of the pigs. ► The same probiotic strain at different doses exerted qualitatively different effects.