Expression of FimH Enhances Trafficking of an Orally Delivered Vaccine to Immune Inductive Sites via Antigen-Presenting Cells.

The development of lactic acid bacteria as mucosal vaccine vectors requires the identification of robust mucosal adjuvants to increase vaccine effectiveness. The type I fimbriae adhesion protein FimH is of interest as a mucosal adjuvant as it targets microfold (M) cells enhancing vaccine uptake into Peyer's patches and can activate the innate immune system via Toll-like receptor (TLR) 4 binding. Here, we displayed the N-terminal domain of FimH on the surface of a vaccine vector and evaluated its ability to increase uptake of into Peyer's patches and activate innate immune responses.