Surface display of LukF-PV on Bacillus subtilis spore for oral administration.

AIM: Bacillus subtilis spores are promising candidates for oral vaccine, serving as carriers for foreign proteins from pathogens. Here we utilized CotB, a spore coat protein, to anchor the LukF-PV from Staphylococcus aureus onto the surface of B. subtilis spores. Our goal was to generate a new B. subtilis strain and assess the capacity of the recombinant spore strain to induce antibody production in mice. METHODS: The fusion sequence of cotB-lukF-PV was cloned into E. coli and transformed into B. subtilis HT800F. Colony PCR confirmed the generation of the recombinant strain. SporeELISA verified the display of LukF-PV. Mice were orally gavaged with the spore, and the production of IgA antibodies in feces and IgG in blood was evaluated. RESULTS: We generated a new B. subtilis strain, BsHT2332, that integrated the PcotB-cotB-lukF-PV into its genome at amyE locus. BsHT2332 successfully displayed LukF-PV on the spore surface. The recombinant spores induced significant IgA and IgG immune responses in mice. CONCLUSION: This study demonstrated that B. subtilis spores expressing the S. aureus antigen LukF-PV can induce an immune response. These findings underscore the potential of the B. subtilis spore platform as a promising approach for vaccine development against S. aureus.