Gram-positive commensal bacteria for mucosal vaccine delivery.

To avoid the use of engineered pathogens for vaccine delivery, systems have been developed that allow the expression of heterologous antigens in commensal Gram-positive bacteria. In some cases, both a serum IgG and secretory IgA response are induced to the recombinant protein after vaccination, verifying the validity of the approach. These live recombinant bacteria may be used in the future to introduce a protective immune response to pathogenic microorganisms after mucosal colonization.