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目的探讨湖南地区幽门螺杆菌(Helicobacter pylori,H.pylori)细胞毒素相关基因(CagA基因)3’端可变区序列特征及其与胃十二指肠疾病的关系。方法本地区有明显上消化道症状患者235例,其中慢性胃炎(CG)57例,胃溃疡(GU)62例,十二指肠溃疡(DU)70例,胃癌(GC)46例。于胃镜检查时用灭菌活检钳取胃窦组织1块,分离培养出H.pylori 89株,用PCR法对上述菌株的CagA基因扩增及测序,并通过生物信息学软件进行多重序列比对和相似性分析。结果 H.pylori培养阳性率为37.9%(89/235),其中H.pylori CagA阳性者占91.7%(77/84),GU组、DU组和GC组CagA阳性率高于CG组,其差异有统计学意义(P<0.05)。77株H.pylori CagA基因3’端均具有3个EPIYA重复序列,其中第2个EPIYA序列存在3种突变型,占18.2%(14/77)。H.pylori CagA基因3’端序列特征以东亚型为主,占88.3%(68/77),东亚型的CagA阳性菌株在GU组、DU组及GC组高于CG组(P<0.05)。所有东亚型CagA阳性菌株CagA序列特征类似于Yamaoka报道的A型。结论湖南地区H.pylori CagA阳性菌株以东亚型为主,均具有3个EPIYA重复序列,其中第2个序列存在3种突变型,其与消化性溃疡和胃癌发生有关。
Objective To investigate the 3 ’variable region sequence of Helicobacter pylori (Hpylori) cytotoxin related gene (CagA gene) and its relationship with gastroduodenal disease in Hunan province. Methods There were 235 patients with obvious upper gastrointestinal symptoms in this area, including 57 cases of chronic gastritis (CG), 62 cases of gastric ulcer (GU), 70 cases of duodenal ulcer (DU) and 46 cases of gastric cancer (GC). In the gastroscopy with biopsy forceps to take a sinusoidal tissue, isolated and cultured H.pylori 89 strains, the CagA gene amplification and sequencing of these strains by PCR, and multiple sequence alignment by bioinformatics software And similarity analysis. Results The positive rate of H.pylori culture was 37.9% (89/235), and the positive rate of H.pylori CagA was 91.7% (77/84). The positive rate of CagA in GU group, DU group and GC group was higher than that in CG group There was statistical significance (P <0.05). There were three EPIYA repeats in the 3 ’end of the 77 H.pylori CagA genes, of which 3 were found in the second EPIYA sequence, accounting for 18.2% (14/77). The 3 ’end sequences of CagA gene of H.pylori were predominantly of East Asian type, accounting for 88.3% (68/77). The CagA positive strains of East Asian type were higher in GU group, DU group and GC group than CG group (P <0.05). The CagA sequence characteristics of all East Asian CagA positive strains are similar to the type A reported by Yamaoka. Conclusions The H.pylori CagA positive strains in Hunan Province are mostly of East Asian type, and all have three EPIYA repeats, of which there are three mutant types in the second sequence, which are associated with peptic ulcer and gastric cancer.