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Background: Helicobacter pylori (Hp) adhesion, BabA, is localized on the bacterial cell surface, binds to the fucosylated Lewis b histo-blood group antigen on gastric epithelial cells and is responsible for bacterial colonization in the gastric milieu. The diverse roles of this bacterial adhesion in Hp-induced pathogenesis remain understudied.

Methods: We have isolated single colonies of Hp from 156 (NUD=97, DU=34, GC=25) patients. babA and babB genes were evaluated by gene/locus-specific PCR. BabA protein expression and Lewis b (Leb) binding capacity were determined by immunoblotting and ELISA, respectively.

Results: Leb binding assay identified 36% of the strains as high binders and the remaining 64% with low binding capacity. All (100%) of the strains in the former group expressed BabA protein at high levels (BabA-H). Of the latter group, 40% were BabA low producers (BabA-L) and the remaining 60% produced no detectable BabA protein (BabA-Neg). The majority (73/88, 83%) of the strains expressing BabA protein were babA gene-positive at locus A versus. those at locus B (15/88, 17%, P = 0.034). The same holds true for Lewis b binding. In other words, the former group constitutes larger numbers (44/50, 88%) of Leb high-binders relative to the latter group (6/50, 12%, P = 0.035). Furthermore, amongst the former group, co-presence of babA and babB genes in locus A reduced the probability of Leb binding (P = 0.0001).

Conclusion: Presence of babA gene in locus A is associated with higher BabA protein expression and Lewis b binding. Therefore, gene/locus-specific PCR seems better suited for the assessment of functional BabA protein.