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Toxigenicity of Helicobacter pylori isolates possessing cagA gene and vacuolating cytotoxin.

Inflammatory cells in the gastric epithelium and direct cell damage are important effects of H. pylori infection in causing gastroduodenal diseases. The aim of this study was to determine whether H. Pylori possessing the cagA gene and vacuolating cytotoxin activity (cagA+/tox+) has these toxigenicities. The detection of cagA was performed by the polymerase chain reaction method. Culture supernatants of H. pylori were tested on rabbit gastric epithelial cell culture for intracellular vacuolation. H. pylori isolates were divided into two major types, cagA+/tox+ and cagA-/tox- strains. Ten Japanese monkeys were allocated to two groups, with six animals inoculated with the cagA+/tox+ strain and four animals inoculated with the cagA-/tox- strain. Five other Japanese monkeys served as controls. They were observed endoscopically every week and the severity of gastritis was evaluated in biopsy specimens obtained from the antral mucosa. Histopathological examination of the gastric mucosa revealed a more severe neutrophil infiltration caused by the cagA+/tox+ strain than that caused by the cagA-/tox- strain for 3 months after inoculation. These findings indicate that cagA and vacuolating cytotoxin may be important factors in causing the severe damage of the human gastric mucosa produced by H. pylori.