Determination of Helicobacter pylori virulence by simple gene analysis of the cag pathogenicity island

Nucleic acid amplification was performed for five loci in the cag pathogeni city island (PAI) of Helicobacter pylori (comprising cagA, the cagA promote r region, cagE, cagT, and the left end of cagII [LEC]), and gastric inflamm ation in patients was evaluated. Of 204 H. pylori isolates from Japanese pa tients (53 with peptic ulcer, 55 with gastric cancer, and 96 with chronic g astritis), 197 (96.6%) were positive for all five loci. Two isolates (1%) w ere negative for all five loci, and five isolates (2.4%) were positive for only cagA and LEG. These Latter seven isolates were all from patients with mild chronic gastritis. Neutrophil infiltration in gastric mucosa was signi ficantly milder in patients infected with partially or totally deleted-PAI strains than in those with intact-PAI strains. The cagE gene was a more acc urate marker of an intact cag PAI than the cagA gene, and cagE seemed to be more useful in discriminating between H, pylori strains causing different rates of disease progression.