Classification of VacA,a cytotoxin produced by Helicobacter pylori, based on gene analyzes

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Clinical features of Helicobacter pylori infection vary widely among patients. Production of the cytotoxin VacA has been alleged to be responsible for virulence by several reports from Western countries. This research sought to confirm the VacA-related virulence in Japan.This research has revealed, however, that most H.pylori isolates in Japan are positive for VacA irrespective of gastroduodenal status in the hosts. The cytotoxin activity in the supernatant of bacterial culture was usually positive, and the nucleotide sequence analysis of vacA gene revealed cytotoxinsecreting genotype. By using recombinant VacA expressed in E.coli, we further confirmed the production of VacA by bacterial isolates and the seropositivity of anti-VacA antibody in Japanese patients.It was concluded that VacA is not the major virulence determinant factor in Japan. However, the high prevalence of VacA-positive strains may be related to the high incidence of gastric cancer in Japan.