IL-1 Fragment Modulates Immune Response Elicited by Recombinant Bacillus subtilis Spores Presenting an Antigen/Adjuvant Chimeric Protein.

Mucosal immunizations are convenient ways of vaccination, which do not require any trained personnel for administration. One of the major challenges for developing an effective mucosal vaccine is finding appropriate adjuvant. Bacillus subtilis endospores have been shown to help solving these obstacles while serving as a platform for presentation of both, antigens and adjuvants. In this study, we have successfully designed and constructed recombinant spores displaying an antigen/adjuvant chimeric protein. We have used a fragment of Clostridium difficile flagellar cap FliD protein as antigen and VQGEESNDK peptide, a fragment of human IL-1β, as adjuvant. Recombinant spores presenting FliD were able to elicit immune response in orally immunized mice which could be evaluated by detection of FliD-specific IgA antibodies in feces of immunized animals. Moreover, the presence of IL-1β fragment significantly changed characteristics of elicited immune response. Obtained results show that recombinant spores presenting an antigen/adjuvant chimeric protein exhibit both properties in mucosal immunization of mice. Moreover, IL-1β fragment could serve as valuable adjuvant in B. subtilis spore-based mucosal vaccines.