Extended Data Fig. 7: Schematic summary of the findings in this study.
From: Microbiota-targeted maternal antibodies protect neonates from enteric infection
Top, mNabs induced by commensal microbiota in dams were transferred to neonates through the breast milk. Cross-reacting mNabs (especially IgG antibodies) were detected that bound to the pathogenic, non-indigenous bacterial species ETEC and correlated with protection against disease in pups challenged with ETEC. IgG antibodies were also shown to be transported from the milk to the bloodstream of pups by a process that we call IgG retro-transport. Bottom, mNabs react with many commensal species and among them an Enterobacteriaceae isolate (Pantoea) was found to induce antibodies that cross-react with ETEC. The immunogenicity of this commensal species is hypothesized to be a result of local antigen-sampling processes that involve dendritic cells and uptake by Peyer’s patch germinal centres. This ultimately leads to the induction of high-affinity IgGs directed against a Pantoea antigen that cross-reacts with ETEC. IgG was also shown to be transported from the blood stream to the intestinal lumen by FcRn in adult mice. Illustrations were created with BioRender (https://biorender.com/).
