ABSTRACT
Rice bran (RB) contains a distinct stoichiometry of phytochemicals that can promote gut mucosal immune responses against enteric pathogens. This chapter describes studies demonstrating that RB alone or together with probiotics reduces rotavirus diarrhea and norovirus infection and diarrhea, and the ability of RB to enhance the protective efficacy of the AttHRV vaccine in Gn pigs. RB feeding significantly protected against diarrhea upon virulent HRV challenge and enhanced the protective rate of the vaccine against rotavirus diarrhea to 100%. RB significantly increased IFN-γ-producing T cell responses in intestinal and systemic lymphoid tissues. Furthermore, RB also increased the number of total IgM- and IgA-secreting cells, total serum IgM, IgG, and IgA titers, and HRV-specific IgA titers in intestinal contents. A cocktail regimen with Lactobacillus rhamnosus and Escherichia coli Nissle 1917 colonization plus RB feeding exhibited high protection against HuNoV diarrhea and shedding. The diarrhea reduction rates were 78% compared with the control group, and diarrhea severity was also significantly reduced. The high protective efficacy of the regimens was attributed to stimulation of IFN-gamma T cell responses, increased production of intestinal IgA and IgG, and maintenance of healthy intestinal morphology. The probiotic-RB regimens may represent highly efficacious strategies to prevent and treat HRV and HuNoV gastroenteritis.
