Genetic diversity of the Helicobacter pylori haemagglutinin/protease (hap) gene.

Helicobacter pylori has been associated with the etiology of gastritis, gastric and duodenal ulcers and gastric cancer in man. In this study we confirm the presence of the haemagglutinin/protease (hap) gene in ten geographically diverse strains of H. pylori, but the Southern analysis of genomic DNA suggested that the location of the hap gene was different in each strain. We suggest that the hap gene is subject to a high rate of mutation and subsequent polymorphisms by virtue of a mobile, genetic element located upstream of the hap gene in the H. pylori genome. Simple transformation experiments suggested that this polymorphism may be mediated by a transposon-like element.