Isolation of recombinant protective Helicobacter pylori antigens

A total of seven clones producing both new and previously described Helicob acter pylori proteins were isolated from a library of H. pylori genomic DNA . The screening approach by which these proteins were detected relied on th e use of antisera raised in mice vaccinated with Helicobacter felis sonicat e plus cholera toxin, a regimen which protects mice from H. pylori challeng e, This strategy was designed to maximize the possibility of obtaining anti gens which might be capable of conferring protection from H. pylori infecti on. Two of the clones were shown to encode the urease enzyme and the heat s hock protein HspB, which have already been identified as protective antigen s. The other five clones were sequenced, protein coding regions were deduce d, and these sequences were amplified by PCR for incorporation into Escheri chia coli expression vectors. The proteins produced from these expression s ystems were purified to allow testing for protective efficacy in an H. pylo ri mouse model, All five proteins were able to facilitate the clearance of a challenge with H. pylori, as judged by an assay of gastric urease activit y and light microscopy on stomach sections. These results clearly indicate that the screening strategy has successfully identified candidate vaccine a ntigens.