Gut-resident C. perfringens impedes rotavirus vaccine efficacy.

Background & Aims: The extent to which live orally-administered rotavirus (RV) vaccines elicit protective immunity is highly heterogeneous. We hypothesized microbiota composition might influence vaccine efficacy.

Methods: We tested this concept by examining extent to which colonizing mice with segmented filamentous bacteria (SFB) influenced RV vaccine efficacy.Influence of human microbiomes on RV vaccination was studied via administering germ-free mice fecal microbial transplants (FMT) from children with robust or minimal RV vaccine responsiveness. Post-FMT, mice were subjected to vaccination and challenge doses of RV.

Results: SFB administration resulted in a phenotype reminiscent of RV vaccine failure, i.e. minimal generation of RV antigens and, consequently, lack of anti-RV antibodies resulting in proneness to RV challenge once SFB levels diminished. Transplant of microbiomes from children to mice recapitulated donor vaccination phenotype. Specifically, mice receiving FMT from high-responding children exhibited high levels of fecal RV antigen shedding and RV antibodies in response to RV vaccination and, concomitantly, were impervious to RV challenge. In contrast, mice receiving FMT from children who had not responded to RV vaccination exhibited only modest responses to RV challenge and, accordingly, remained prone to RV challenge. Microbiome analysis ruled out a role for SFB but suggested that RV vaccine failure might involve . Oral administration of cultured to gnotobiotic mice partially recapitulated the RV vaccine non-responder phenotype. Analysis of previously-reported microbiome data found C. perfringens abundance in children associated with RV vaccine failure.

Conclusion: Microbiota composition influences RV vaccine virus infection and, consequently, protective immunity. may be one, perhaps of many, bacterial species harbored in the intestine of RV-vaccine non-responders that influences RV vaccine outcomes.