Regional variation among vacA alleles of Helicobacter pylori in China.

Allelic variation among Helicobacter pylori vacA occurs in the signal and middle region of the gene. The aim of the study was to investigate alleleic variation of vacA among H. pylori strains from three regional areas of China and the relationship between vacA alleles and PUD. DNA extracted from 88 clinical isolates of H. pylori was analyzed by type-specific PCR and reverse hybridization line probe assay (LiPA) to determine the genotype of vacA and presence of cagA. In 87 isolates, all of the vacA alleles could be classified as either type s1c or type s1a, and all could be classified as m1, m2a, or m2b. One strain could not be typed. In all, 41% of patients were infected with multiple vacA genotypes, with the highest level being observed in Shanghai (63%). In strains from Beijing, s1a was dominant; by contrast, s1c was dominant in Guangxi and Shanghai. The prevalence of m2b strains in Shanghai (63%) was significantly higher than that in Beijing (3%) or Guangxi (0%). Thirty of the 87 patients had peptic ulcers. However, there was no association between vacA genotype and PUD. This study demonstrates that there is significant geographic diversity of genotype of vacA within China. The absence of vacA s2 genotypes precluded analysis of an association of vacA s genotypes and clinical disease.