Length polymorphism of cagA genotype in Helicobacter pylori isolates and its clinical significance / 解放军医学杂志

ABSTRACT

Objective To investigate the relationship of the distribution and heterogeneity of cagA gene of Chinese H. pylori isolates with Hp-associated gastroduodenal!diseases in China. Methods Pairs of oligonucleotide primers flanking a conservative 297bp segment and the variable segment of 3' region of cagA gene were designed according to the conserved cagA sequences, and the distribution of cagA gene in 82 Chinese H. pylori isolates and the heterogeneity of variable segment of cagA gene 3' region of 77 H. pylori strains were determined with PCR. Results 77(93.9%) of 82 Chinese Hp isolates were found to be cagA-positive by PCR amplification of the 297bp segment. The variable segment of 3' region of cagA genes was detected in 71(93.9%) of 77 Chinese H. pylori strains, including two without 297bp amplicon, with predominance of PCR products of about 825bp which were designated as type Ⅰ in China. Conclusion The prevalence of cagA is high in Chinese Hp isolates, and the cagA of type Ⅰ with the shortest variable 3' region predominates in China. Neither cagA nor the length of cagA 3' region is associated with the clinical outcome of Hp infection.