| Summary: | <p>Abstract</p> <p>Background</p> <p>The incidence of gastric cancer differs among countries in Asia, and it has been suggested that virulence factors associated with <it>Helicobacter pylori </it>are partly responsible. The aim of this study was to investigate several genetic factors regarded as virulence or molecular epidemiologic markers in <it>H. pylori </it>isolates from Vietnamese subjects.</p> <p>Results</p> <p>The <it>cagA</it>, <it>vacA </it>and <it>cag </it>right-end junction genotypes of 103 <it>H. pylori </it>strains from Vietnam (54 from Hanoi and 49 from Ho Chi Minh) were determined by PCR and sequencing. Three types of deletion in the region located upstream of the <it>cagA </it>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 irrespective of geographical location in the country or clinical outcome. All of the 39-bp and 18-bp deletion-type strains possessed the East Asian type <it>cagA </it>repeat region. The type II <it>cag </it>right-end junction genotype was predominant (84%). The <it>vacA </it>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.</p> <p>Conclusion</p> <p>Pre-EPIYA-region typing of the <it>cagA </it>gene could provide a new genetic marker of <it>H. pylori </it>genomic diversity. Our data support the hypothesis that <it>vacA </it>m1 is closely associated with gastric carcinogenesis.</p>
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