Study On Epiya Motif Polymorphisms Of Helicobacter Pylori Caga C-Terminal Region And Relation To Gastroduodenal Diseasea In Chongqing

Objective:The relationship between EPIYA motif type of Helicobacter pylori (H. pylori) CagA protein and the category of gastroduodenal disease has been controversial. The aim of this study is to investigate the EPIYA motif polymorphisms of H. pylori CagA C-terminal region in China and evaluate the correlation between the EPIYA type and the disease outcome.Methods:H. pylori strains were isolated from gastric biopsy specimens collected from patients with gastroduodenal symptoms in Chongqing, China. The genomic DNA was extracted and the PCR amplification was conducted to study the variations of EPIYA motifs in CagA C-terminal region. The EPIYA types, determined by PCR amplification, were further verified by DNA sequencing in some H. pylori strains. Finally, statistical methods were used to assess relationship between EPIYA type and the category of gastroduodenal diseases.Results:A total of 300 H. pylori strains was isolated from 760 patients with gastric pathologies. Of the isolated H. pylori strains,292 (97.33%) strains were cagA gene positive. But cagA was not correlated with the type of gastroduodenal diseases (P>0.5). Of the cagA positive strains,19 (6.51%) were found multiply H. pylori infected. The probability of mixed infection in Gastric carcinoma is higher than in non-ulcerative gastritis (OR=4.46, 95%CI=1.17 to 17.03). The rest 273 (93.49%) strains were proved to be of single infection, which comprised 254 (93.04%) EPIYA-ABD type strains, 8 (2.93%) EPIYA-ABC type strains,5 (1.83%) EPIYA-AB type strains,3 (1.10%) EPIYA-AABD type strains,2 (0.73%) EPIYA-AD type strains and 1 (0.37%) EPIYA-BD type strain. No correlation was found between EPIYA type and gastroduodenal disease type. Besides,8 mutants of EPIYA were found in EPIYA-B segment of the total analyzed 50 strains. EPIYA mutated to EPIYT in 5 strains, to ELIYA in 1 strain, to ESIYA in 1 strain and to EPVYA in 1 strain. The EPVYA sequence is the first reported EPIYA mutant.Conclusion:The major EPIYA type in H. pylori strains in this study is EPIYA-ABD. Neither CagA nor its C-terminal EPIYA type was correlated with the category of gastroduodenal disease in Chinese patients. But the probability of mixed infection in Gastric carcinoma is higher than in non-ulcerative gastritis.