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Background and purpose of Helicobacter pylori (Helicobacter pylori, H.pylori) is a kind of colonization in the human gastric mucosa Gram-negative , spiral micro- aerobic . Chronic H.pylori infection is considered a major cause of gastritis and peptic ulcer and with gastric adenocarcinoma and gastric mucosa-associated lymphoid tissue lymphoma related to 1994 by WHO as Class Ⅰ carcinogen . H.pylori infection rate is very high, above 70% in developing countries , while in developed countries has reached 20 to 50%. Ours is a high incidence of chronic gastric diseases countries , the incidence rate of chronic gastritis total population of 20 to 30% , some of which can occur even gastric ulcer . H.pylori exact pathogenesis is not fully understood , the Western studies suggest that , H.pylori strains caused by different genotypes virulence differences may be the main reason for produce different clinical outcomes . Epidemiological data show that a large number of experimental investigations , cagA, vacA, iceA and babA isogenic with peptic ulcer disease and ( or ) the incidence of gastric cancer is closely related to , but the East , the West 's findings are not entirely consistent , therefore , H.pylori specific pathogenic factor has been the focus for researchers . Ando and other limitations in the study of H.pylori - modification (RM) system, found a potential virulence factor - restriction endonuclease enzyme replacement gene (H.pylori restriction endonuclease-replacing gene, hrgA), the gene in 34% of the tested strains replacing type Ⅱ RM systems hpy Ⅲ R gene and cagA -positive patients with gastric cancer in Asian strains of H.pylori positive rate was significantly higher than non- cancer patients , it is thought to be with H.pylori another causative factor for gastric cancer . However, China has not been reported about hrgA genes . In addition , there are more studies concluded that , cagA gene -positive strains of H.pylori infection and peptic ulcer , intestinal metaplasia , atrophic
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