Characterization of CagA variable region of Helicobacter pylori isolates from Chinese patients.

ABSTRACT

AIM: To characterize the CagA variable region of Helicobacter pylori isolates from Chinese patients. METHODS: DNA fragments in CagA variable region were amplified and sequenced respectively from genomic DNA of 19 isolates from patients with gastric cancer and 20 isolates from patients with chronic gastritis. The tendency of phosphorylation in tyrosine(s) of CagA proteins was evaluated subsequently by phosphorylation assay in vivo and in vitro respectively. RESULTS: About 97.44% (38/39) H pylori isolates possessed CagA gene. CagA(+) strains contained 2-4 tandem five-amino-acid motifs EPIYA but only one EPIYA had repeated sequence in CagA variable region in different isolates. There was no significant difference between the number of EPIYA motifs in H pylori from patients with different diseases. However, only tyrosine site in EPIYA within repeated sequence could be phosphorylated by AGS cells in vivo although all tyrosine sites in EPIYA could be phosphorylated in vitro. CONCLUSION: CagA in Chinese has no functional difference in perturbing cellular signal pathway among different H pylori isolates.