Immunogenicity of self-adjuvanticity oral vaccine candidate based on use of Bacillus subtilis spore displaying Schistosoma japonicum 26 KDa GST protein

One of the promising approaches in mucosal immunization relies on live recombinant vaccine carriers. In this study, we used a six-extracellular protease-deficient Bacillus subtilis strain WB600 to express Schistosoma japonicum 26 kDa glutathione S-transferase (GST). Western blot, immunofluorescence, and flow cytometry analyses were used to identify SjGST expression on spore surface. SjGST recombinant spores were used for oral vaccination in mice and were shown to generate mucosal and systemic response. Both SjGST-specific secretory IgA in feces and IgG in serum augmented significantly on day 33 after oral administration. It seemed that surface display of recombinant S. japonicum SjGST on B. subtilis WB600 spores showed good immunogenicity, and B. subtilis spores could be used as potential mucosal delivery vehicles to provide more effective vaccination strategies for parasite prevention and control in the future.