فهرست نشریات علمی دسترسی آزاد ایران

Objectives: Existence of cytotoxin associated gene A ( cagA ) is considered as a marker for detection of an oncogenic Helicobacter pylori strain. Expression of cagA in the strains with incomplete delivery system (partial Cag PAI) could convert them to less virulent strains. This study was aimed to analyze expression of cagA in H. pylori strains presenting diverse cag PAI and its effect on histopathological changes of the gastric tissue. Methods: Clinical strains of H. pylori and related histopathological data were obtained to examine the presence of 12 cag PAI segments by PCR. Expression of cagA was analyzed by RT-PCR as well as Immunoblotting on RNA and protein extracts of the cag PAI-positive strains, respectively. In situe expression of Cag A-positive strains was determined in a gastric epithelial cell line. Results: Intact cag PAI was detected among 33% (4/12) of H. pylori strains. Out of 7 diverse cag PAI genotypes in these strains, expression of cag A was confirmed in 2 strains with complete cag PAI at both RNA and protein levels. Occurrence of intestinal metaplasia and severe active gastritis were mainly detected in the strains with complete cag PAI genotype. No association was detected between EPIYA types of the strains and expression of cag A. Conclusions: These results collectively showed high diversity of cag A and cag PAI among the H. pylori strains. These diversities may provide some reasons to explain distinct disease severity caused by different H. pylori strains in the gastric tissue.