The combination of recombinant and non-recombinant Bacillus subtilis spore display technology for presentation of antigen and adjuvant on single spore

Bacillus subtilis spores can be used for presentation of heterologous proteins. Two main approaches have been developed, the recombinant one, requiring modification of bacterial genome to express a protein of interest as a fusion with spore-coat protein, and non-recombinant, based on the adsorption of a heterologous protein onto the spore. So far only single proteins have been displayed on the spore surface.

We have used a combined approach to adsorb and display FliD protein of Clostridium difficile on the surface of recombinant IL-2-presenting spores. Such spores presented FliD protein with efficiency comparable to FliD-adsorbed spores produced by wild-type 168 strain and elicited FliD-specific immune response in intranasally immunized mice.

Our results indicate that such dual display technology may be useful in creation of spores simultaneously presenting adjuvant and antigen molecules. Regarding the characteristics of elicited immune response it seems plausible that such recombinant IL-2-presenting spores with adsorbed FliD protein might be an interesting candidate for vaccine against infections with Clostridium difficile.