Exploring novel vaccines against Helicobacter pylori: protective and therapeutic immunization

Infection of human stomach by Helicobacter pylori, a gram negative spiral b acterium first isolated in 1983 from a patient with chronic active gastriti s (1), causes nearly all duodenal ulcers and most gastric ulcers and is ass ociated with an increased risk of gastric adenocarcinoma (2). Current thera pies for gastric infections include combination triple or quadruple therapy of antimicrobial and/or antiulcer agents for eradication of H. pylori infe ction (3). Development of the resistant strains and ecological niche (habit ant) of the bacteria may cause relapse after the termination of the therapy . However, if effective, the high cost, difficulty of patient compliance an d risk of selection for resistant strains make these therapeutic regimens i mpractical on a large scale, though effective on the laboratory trial stage s. Studies of the pathogenesis of H. pylori have led to the identification of bacterial antigens and adherin proteins as candidates for inclusion as n ovel vaccines against these diseases (4-7). Both prophylactic and therapeut ic vaccination have been demonstrated in animal models of H. pylori infecti on (8-10).