Combined prebiotic and microbial intervention improves oral cholera vaccination responses in a mouse model of childhood undernutrition

Undernourished children in low-income countries often exhibit poor responses to oral vaccination. Perturbed microbiota development is linked to undernutrition but whether and how microbiota changes affect vaccine responsiveness remain unclear. Here, we show that gnotobiotic mice colonized with microbiota from undernourished Bangladeshi children and fed a Bangladeshi diet exhibited microbiota- dependent differences in mucosal IgA responses to oral vaccination with cholera toxin (CT). Supplementation with a nutrient-rich diet consisting of spirulina, amaranth, flaxseed and micronutrients augmented CT-IgA production. Mice initially colonized with a microbiota associated with poor CT responses exhibited improved immunogenicity upon invasion of bacterial taxa from cagemates colonized with a more 'responsive' microbiota. Additionally, a consortium of five cultured bacterial invaders conferred augmented CT-IgA responses in mice fed the supplemented diet and colonized with the 'hypo- responsive' community. These results provide preclinical proof-of-concept that diet and microbiota influence mucosal immune responses to CT vaccination and identify a candidate synbiotic formulation.