Intact cag pathogenicity island of Helicobacter pylori without disease association in Kolkata, India

Several genes including the cagA in the cag pathogenicity island (cag PAI) of Helicobacter pylori are thought to be associated with the gastroduodenal diseases and hence variation in the genetic structure of the cag PAI might be responsible for different clinical outcomes. Our study was undertaken to characterize the cag PAI of H. pylori strains from duodenal ulcer (DU) patients and asymptomatic or non-ulcer dyspepsia (NUD/AV) subjects from Kolkata, India. Strains isolated from 52 individuals (30 DU and 22 NUD/AV) were analyzed by PCR using 83 different primers for the entire cag PAI and also by dot-blot hybridization. Unlike H. pylori strains isolated from other parts of India, 82.6 % of the strains used in this study had intact cag PAI, 9.6 % had partially deleted cag PAI, and 7.7 % of the strains lacked the entire cag PAI. Dot-blot hybridization yielded positive signals in 100 % and 93.8 % of PCR-negative strains for HP0522-523 and HP0532-HP0534 genes, respectively. An intact cagA promoter region was also detected in all cagA-positive strains. Furthermore, the expression of cagA mRNA was confirmed by RT-PCR for the representative strains from both DU and NUD/AV subjects indicating the active cagA promoter regions of these strains. A total of 66.7 % of Kolkata strains produced a ~390-bp shorter amplico