Analysis of virulence factors of Helicobacter pylori isolates from Vietnam

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Helicobacter pylori is recognized to play a causative role in the pathogenesis of gastric cancer. The aim of this study was to investigate several genetic factors regarded as virulence or molecular epidemiologic markers in H. pylori isolates from Vietnamese subjects. The cagA, vacA and cag right-end junction genotypes of 103 H. pylori strains from Vietnam were determined by PCR and sequencing. Three types of deletion in the region located upstream of the cagA Glu-Pro-Ile-Tyr-Ala (EPIYA) repeat region were identified : the 39-bp deletion type, the 18-bp deletion type, and the no-deletion type. The majority of strains studied (77% ; 80/103) had the 18-bp deletion. The vacA m1 genotype was significantly more common in strains isolated in Hanoi, where the incidence of gastric cancer is higher, than in strains from Ho Chi Minh.