Background: The cag pathogenicity island (cag PAI) is a major virulence factor. The ability of Helicobacter pylori to adhere to gastric epithelial cells is an important initial step for virulence. The aim of this study was to evaluate the relationship between genetic variations of cag PAI in Japanese clinical isolates and the ability of H. pylori to adhere to gastric epithelial cells.
Materials and methods: The polymerase chain reaction and Southern blot analysis were used to verify the presence or absence of cagA, cagE, cagG, cagI and cagM in the cag PAI in 236 Japanese clinical isolates. The ability of H. pylori to adhere to KATOIII cells was examined by flow cytometry.
Results: Seven (3.0%) cag PAI partial-deleted strains were found in 236 clinical isolates, and these strains showed three patterns in the deleted region within the cag PAI. All of the cagG-deleted strains showed decreased adherence to KATOIII cells, in comparison with cagG-positive strains. These strains had abolished IL-8 induction despite the presence of cagE, which is essential for IL-8 induction.
Conclusions: Our results suggest that cagG or surrounding genes in the cag PAI has a function related to adhesion to epithelial cells.