Abstract
Helicobacter pylori (H. pylori) is a human-specific gastric pathogen that colonizes in the stomachs of at least half the world’s population. Both microbial and host factors might determine the outcome of colonization. Epithelial attachment of H. pylori can be mediated by the blood-group antigen-binding adhesin (BabA) targeting human Lewisb surface epitopes. Recently, the gene encoding functional BabA has been cloned and termed babA2. The presence of babA2, vacA and cagA (“triple-positive” strains) showed a highly significant correlation to the presence of ulcer and adenocarcinama. In an effort to investigate the divergent middle region of bab gene polymorphism of Taiwanese clinical isolates, 87 strains were characterized by HaeIII DNA digestion of the bab gene PCR fragments. 13 distinct RFLP patterns and combinations were revealed. DNA sequence analysis of the middle region showed that these regions were identical to Western babA or babB gene (87-89% identity), and were even more conservative among Taiwanese isolates. Further DNA sequence analysis of the bab gene signal peptide region, most of the isolates were highly homologous to the babA2 signal peptide sequence. No 10 bp deletion in the signal peptide region just like babA1 was found in the analyzed strains. Southern blot hybridization of the genomic DNA showed that one or two copies of bab gene might be found in different H. pylori strains.