浙江地区幽门螺杆菌临床菌株vacA优势基因型及其核苷酸序列分析

Analysis on the vacA dominant genotypes and their nucleotide sequences of Helicobacter pylori isolates in Zhejiang area

目的 :了解浙江地区消化性溃疡和慢性胃炎患者感染的幽门螺杆菌 (Hp) vac A优势基因型及其序列特点。方法 :分别从 2 9例消化性溃疡和 34例慢性胃炎患者的胃窦、胃体粘膜组织中分离出 12 6株 Hp。采用聚合酶链反应检测 vac A基因的信号区 (s)和中间区 (m)亚型 ,部分优势基因型的扩增产物 T- A克隆后进行核苷酸序列测定。结果 :所有菌株均扩增出 vac A s区和 m区基因片段 ,发现 s1a/ m1、s1a/ m2、s1a/ m1b、s1a/ m1b- m2 4种基因型 ,其比例分别为 7.1% (9/ 12 6)、61.9% (78/ 12 6)、2 9.4 % (37/ 12 6)、1.6% (2 / 12 6)。 17.5 %患者 (11/ 63)存在不同 vac A基因型Hp菌株混合感染 ,但在胃炎组和溃疡组中的分布差异无显著性 (P>0 .0 5 )。 6株 s1a型 Hp菌株的 s区扩增产物与报道的 s1a型 60 190株核苷酸序列同源性为 93.15～ 94 .86% ,4株 m2型 Hp菌株的 m区扩增产物与报道的 m2型 87-2 0 3株核苷酸序列之间同源性为 93.63～ 97.61%。结论 :s1a/ m2和 s1a/ m1b均是浙江地区消化性溃疡或慢性胃炎患者感染的 Hp菌株的 vac A优势基因型 ,部分优势 vac A基因型菌株的核苷酸序列与国外报道的参考菌株有较高的同源性 ;部分患者同时感染多株不同 vac A基因型 Hp。

Objective: To determine vacA dominant genotypes of Helicobacter pylori in patients with peptic ulcer (PU) or chronic gastritis (CG). Methods: H.pylori strains were isolated from mucosa samples of gastric antrum and corpus of patients suffering from PU (n=29) or CG (n=34), 126 strains of H.pylori were selected for PCR to detect s and m regions in vacA gene of the isolates. Parts of the amplification products were sequenced after T-A cloning. The correlation between infection or coinfection with different vacA genotypes of H.pylori and different gastroduodenal diseases was further analyzed. Results: The positive amplification products of vacA gene, s and m regions, were found in the DNA samples of all the isolates. In these products, s1a/m1, s1a/m2, s1a/m1b and s1a/m1b-m2 genotypes of vacA gene were detected and s1b and s2m1a genotypes absent. Proportions of the s1a/m1, s1a/m2, s1a/m1b and s1a/m1b-m2 genotypes were 7.1% (9/126), 61.9% (78/126), 29.4% (37/126) and 1.6% (2/126), respectively. 17.5% (11/63) of the patients were confirmed to be coinfected with different genotype H.pylori strains. No statistical differences were found in the distribution of different genotype H.pylori strain infection in the gastric diseases (P>0.05). In comparison with the reported sequences of H.pylori strain 60190 with s1a genotype and strain 87-203 with m2 genotype, homologies of the nucleotide sequences of s1a PCR products from 6 strains of H.pylori isolates and m2 PCR products from 4 strains of H.pylori isolates were 93.15%~94.86% and 93.63%~97.61%, respectively. Conclusion: H.pylori with s1a/m2 or s1a/m1b are the dominant genotypes in the PU or GC patients in Zhejiang area. The nucleotide sequences of partial amplification products from the vacA dominant genotypes of H.pylori show high homology compared with the reported sequences. Part of the patients may be coinfected with different vacA genotypes of H.pylori.