Characterization of Helicobacter pylori PldA, a phospholipase with a role in colonization of the gastric mucosa

Background & Aims: Phospholipase activity may play a role in the pathogenicity of Helicobacter pylori. Furthermore, some drugs that are effective against H. pylori infection are phospholipase inhibitors. Scrutiny of the H. pylori 26695 genome sequence revealed the presence of a putative protein with homology to Esherichia coli outer membrane phospholipase A (PldA). The aim of this study was to investigate the role of this putative PldA in the pathogenicity of H. pylori. Methods: An isogenic pldA mutant was constructed and analyzed for in vitro phospholipase A 2 and hemolytic activity. Adherence of the mutant to human gastric adenocarcinoma cells and the ability to colonize mice were also investigated. Results: The pldA mutant showed a marked reduction in phospholipase A 2 and hemolytic activity compared with the wild-type strain. The mutant was unable to colonize mice at 2 and 8 weeks, but it did induce a significant immune response. In contrast, the ability of the mutant to adhere to human gastric adenocarcinoma cells was unaffected. Conclusions: The results suggest a role for PldA in colonization of the gastric mucosa and possibly tissue damage after colonization. GASTROENTEROLOGY 1999;117:1098-1104