Expression of an endotoxin-free S-layer/allergen fusion protein in gram-positive Bacillus subtilis 1012 for the potential application as vaccines for immunotherapy of atopic allergy

Background  

Genetic fusion of the major birch pollen allergen (Bet v1) to bacterial surface-(S)-layer proteins resulted in recombinant proteins exhibiting reduced allergenicity as well as immunomodulatory capacity. Thus, S-layer/allergen fusion proteins were considered as suitable carriers for new immunotherapeutical vaccines for treatment of Type I hypersensitivity. Up to now, endotoxin contamination of the fusion protein which occurred after isolation from the gram-negative expression host E. coli had to be removed by an expensive and time consuming procedure. In the present study, in order to achieve expression of pyrogen-free, recombinant S-layer/allergen fusion protein and to study the secretion of a protein capable to self-assemble, the S-layer/allergen fusion protein rSbpA/Bet v1 was produced in the gram-positive organism Bacillus subtilis 1012.