Probiotics and lactogenic immune factors affect neonatal B cell responses to rotavirus vaccine (166.26)

Abstract

Abstract Breast milk (milk/colostrum [cols]) components and gut commensals play important roles in neonatal immune maturation, establishment of gut homeostasis and immune responses to oral vaccines. We investigated the impact of lactic acid bacteria colonization (Lactobacillus rhamnosus strain GG and Bifidobacterium lactis Bb12, probiotics) with/without mother’s milk/cols on B cell responses to an attenuated human rotavirus (RV) vaccine in a neonatal gnotobiotic pig model. Milk/cols did not affect probiotic colonization in RV vaccinated pigs. However unvaccinated pigs fed milk/cols shed higher fecal titers of probiotic bacteria than non-cols/milk fed colonized controls (p<0.05). In RV vaccinated pigs, milk/cols feeding with probiotic treatment resulted in a trend for higher mean serum IgA RV antibody titers and intestinal IgA antibody secreting cell (ASC) numbers compared to milk-fed, non-probiotic colonized pigs. Probiotic colonization alone did not affect IgA RV antibody titers in vaccinated pigs, but serum IgG RV antibody titers (p<0.05) and gut IgG ASC numbers were lower, suggesting that certain probiotics impact RV vaccine responses. In vaccinated pigs, probiotic or milk/cols supplementation did not enhance total intestinal B cell numbers above that induced by attenuated RV vaccine alone. Our findings suggest that probiotics and milk/cols components (soluble mediators), alone or synergistically, modulate neonatal immune responses to oral RV vaccines, requiring further evaluation.