中国人感染幽门螺杆菌中检出cagⅠ的结构差异

Difference between cagA and cagM in cag Ⅰ of Helicobacter pylori isolated from Chinese patients

目的探讨cag致病岛基因群的右半部分cagI中cagA与cagM在中国人群感染幽门螺杆菌(H.pylori)中存在的差异及意义。方法采用PCR方法检测了107例临床分离培养的H.pylori菌株,选择cagI中的cagA和cagM为观测对象,分别扩增cagA中的298bp片段及cagM中的170bp片段。结果 cagA阳性的检出率为92.5％,cagM阳性的检出率为86.9％、cagA,cagM在慢性胃炎、消化性溃疡、胃癌等不同疾病组间的检出率无显著差异(P>0.05),其中cagA与cagM均阳性的检出率为85％(91/107)、cagA阳性、cagM阴性的检出率为7.5％(8/107)、cagA阴性、cagM阳性的检出率为1.9％(2/107),cagA与cagM均阴性的检出率为5.6％(6/107),即在9.4％的H.pylori中,cagA与cagM的检出存在不一致性。结论 cagA与cagM检出的不一致性表明,中国人群感染的H.pylori中,cag致病岛不仅存在cagⅠ与cagⅡ之间分割、重排和缺失,还发现在cagⅠ基因群内部,即在cagA和cagM之间出现新的分割、重排和缺失位点,以及存在新的cag致病岛结构形式。

AIM To investigate the existing difference between cagA and cagM in cag Ⅰ of Helicobacter pylori (H. pylori) isolated from Chinese patients. METHODS Fragments to cagA and cagM in cag Ⅰ was amplified by polymerase chain reaction(PCR) in 107 H. pylori strains from Chinese patients. RESULTS The ampticom to cagA was positive in 99 strains, and fragments to cagM was positive in 93 strains. The positive rate was 92.5% in cagA, and 86.9% in cagM. There was no statistical difference among chronic gastritis, peptic ulcer and gastric carcinoma in the detectable rate of cagA or cagM (P>0.05). Correspondence of existence of cagA and cagM was detected in most of H.pylori strains, but incorrespondent existence of cagA and cagM was found in 9.4% strains. CONCLUSION The presentation of cagA and cagM were predominant in Chinese H.pylori strains, but cagA and cagM in cag Ⅰ could be lost separately. It is suggested that there are some new mechanisms to split cag Ⅰ and, moreover, to delete cag Ⅰ partially.