Background/aims: In Japan, infection with cagA-positive H. pylori is not associated with gastric cancer unlike Western populations. Both cagE and Agrobacterium VirD4 homologue are genes inside the cagPAI. The aim of this study was to examine whether the presence of genes inside the cagPAI, cagA, cagE and Agrobacterium VirD4 homologue, is associated with gastric cancer in Japan.
Methodology: Thirty-nine patients with gastric cancer and 39 subjects with only chronic gastritis were infected with H. pylori. Seventy-eight H. pylori strains were isolated from gastric biopsies and the presence of 23S rRNA, cagA, cagE, and VirD4 homologue were studied by polymerase chain reaction.
Results: The positivity of cagA was 97.4% in patients with gastric cancer, and 92.3% in control subjects. Thirty-six strains (92.3%) isolated from patients and 35 strains (89.7%) from control subjects had both cagE and VirD4. All the 3 cagA-negative strains did not have both cagE and VirD4. There were no significant differences in the positivities of cagA, cagE, and VirD4 between patients and control subjects.
Conclusions: cagE and VirD4 were possessed by most Japanese strains, and thus the structure of the cagPAI of H. pylori might not be associated with the development of gastric cancer in Japan.