Polymorphism of Helicobacter pylori vacA, isolated in China / 中华流行病学杂志

ABSTRACT

Objective To understand the polymorphism of Helicobacter pylori (H. pylori) vacA alleles in China. Methods A total of 119 H. pylori strains were isolated from different gastroduodenal diseases in 7 different geographic regions in China. vacA and its alleles were identified according to the length of PCR products with DNA electrophoresis. The distributions of vacA alleles were statistically analyzed. The core fragment of vacA was sequentially analyzed by software MEGA4.0. Results The alleles in vacA dominantly belonged to sla, m2 and il in the tested strains.The distribution appeared to be 97.5%(116/119) ,68.9%(82/119) and 91.6%(109/119),respectively.The mlb allele appeared to be 26.1% (31/119). slb and mla were not found. The major vacA recombination was between slaim2/il and 62.2% , followed by sla/mlb/il (25.2% , 30/119). No association was found between the distribution of sla allele and the clinical outcome, as well as the geographical regions (P>0.05). However, the distribution of m alleles showed significant difference both among the types of disease and the geographic regions (P<0.01), The present of i alleles did not show significant differences among disease patterns, but had significant differences between different geographic groups (P<0.01). Three clusters were identified among these 119 isolates according to the DNA sequence of vacA. Conclusion sla/m2/il appeared to be the main allele in H. pylori vacA isolates from China in this study. The distribution of m alleles in vacA was correlated both to the regions and the disease patterns. The presence of i allele was associated to the regions but not the disease patterns.