Inducing Mucosal Immunity to Bacterial and Viral Pathogens Using Recombinant Spores as Vaccine Vehicles

Allochthonous bacteria have been shown to play a pivotal role in the control of certain gut pathogens, notably Clostridium difficile and Staphylococcus aureus. One such bacterium is Bacillus subtilis, found in soil but also able to grow within the gut of mammals. This bacterium will be engineered to express heterologous antigens on the spore coat, the spore being the dormant life form formed by starving cells of B. subtilis. Using spores expressing antigens of either SARS-CoV-2 or Helicobacter pylori animals will be dosed nasally (SARS-Cov-2) or orally (H. pylori) and antigen-specific immune responses determined. In both cases immunity will be assessed for its protectivity against challenge with either virus (SARS-Cov-2) or bacteria (H. pylori). Long-term, this approach will be useful for developing prototype mucosal vaccines to either COVID-19 or H. pylori infection (the cause of stomach ulcers and gastric cancer).