Relationship between the cagA 3 ' repeat region of Helicobacter pylori, gastric histology, and susceptibility to low pH

Background & Aims: The variation in size of Helicobacter pylori CagA is rel ated to repeat sequences in the 3' region of the cagA gene. We investigated whether structural subtypes of the cag4 3' region are associated with pres entation of the infection or to susceptibility to acid. Methods: We examine d 319 cagA-positive H. pylori isolates: 84 isolates from Bogota, Colombia; 83 from Houston, Texas; 24 from Siena, Italy; and 128 from Seoul, Korea. Th e cagA 3' region was amplified by polymerase chain reaction. Gastric histol ogy and susceptibility to pH 3 were evaluated in relation to the number of cagA repeat regions. Results: Strains with more than three repeat regions w ere associated with significantly higher scores for gastric mucosal atrophy and intestinal metaplasia than those with fewer repeat regions. H. pylori strains with three repeat regions were also significantly more susceptible to pH 3 than isolates with fewer repeat regions. Conclusions: H. pylori str ains with more than three repeat regions in the 3' region of the cagA gene are associated with enhanced histological injury and with reduced survival in acidic conditions. It is hypothesized that these variants arise within t he stomach.