Exploring novel vaccines against Helicobacter pylori: protective and therapeutic immunization

Infection of human stomach by Helicobacter pylori, a gram negative spiral bacterium first isolated in 1983 from a patient with chronic active gastritis (1), causes nearly all duodenal ulcers and most gastric ulcers and is associated with an increased risk of gastric adenocarcinoma (2). Current therapies for gastric infections include combination triple or quadruple therapy of antimicrobial and/or antiulcer agents for eradication of H. pylori infection (3). Development of the resistant strains and ecological niche (habitant) of the bacteria may cause relapse after the termination of the therapy. However, if effective, the high cost, difficulty of patient compliance and risk of selection for resistant strains make these therapeutic regimens impractical on a large scale, though effective on the laboratory trial stages. Studies of the pathogenesis of H. pylori have led to the identification of bacterial antigens and adherin proteins as candidates for inclusion as novel vaccines against these diseases (4-7). Both prophylactic and therapeutic vaccination have been demonstrated in animal models of H. pylori infection (8-10).