Protection of germ-free mice from infection by Helicobacter felis after active oral or passive IgA immunization.

Helicobacter pylori infection of human gastric epithelium has been associated with gastritis, ulcers and gastric cancers. In an H. felis, germ-free mouse model of infection, oral immunization with bacterial antigens plus cholera toxin resulted in elevated serum, gastric and intestinal anti-H. felis antibody titres and protection from acute infection. Mice given monoclonal IgA anti-H. felis antibody at the time of initial challenge were also protected from infection. These results demonstrate that oral vaccination may be a feasible approach for the prevention of H. pylori infection of humans.