Abstract
Helicobacter pylori shows hemolytic activity when cultured on blood agar plates. Hemolysin is one of potential factors in such an activity. However, the role of H. pylori hemolysin in the clinical pathogenesis and infection mechanism remains to be elucidated. In this study, we compared the hemolytic activities of strains from gastric cancer (GC), gastric ulcers (GU), duodenal ulcers (DU), and non-ulcer dyspepsia (Dys) patients to investigate the relationship among hemolysin and four different diseases. Secondly, we cloned and the tlyA gene that was considered as a key hemolysin in H. pylori from isolates with the highest and lowest hemolytic activity. Thirdly, we constructed the isogenic mutants for assessment of in vitro adherence and hemolytic activity. We also expressed and purified recombinant TlyA in E. coli for future biochemical studies. Among these 98 cases, we found that there were no significant differences of the hemolytic activity among four groups. An alignment and comparison of tlyA between Taiwanese isolates and H. pylori 26695 and J99 showed > 90 % amino acid sequence identity, suggesting that tlyA is a relatively conserved gene in H. pylori. The hemolytic activity of the tlyA knockout mutant was reduced and so did the adherent activity, implicating that TlyA might be related with adherence and infection. These data collectively suggest a positive role of TlyA in H. pylori infection.