中国肠产毒性大肠杆菌中耶尔森菌强毒力岛的检测

Detection of Yersinia high pathogenicity island in enterotoxigenic Escherichia coli strains isolated from China

目的 了解耶尔森菌强毒力岛在中国肠产毒性大肠杆菌中的分布及插入位点。方法 使用PCR扩增、DNA打点杂交和DNA测序及分析方法。结果 在 94株分离自中国的肠产毒性大肠杆菌中 ,14株耶尔森菌强毒力岛核心区的 8个基因PCR扩增阳性 ,除 3株菌的整合酶基因外 ,PCR扩增产物长度均与预期一致 ,但天冬酰胺转运RNA(asnTtRNA)位点扩增阴性 ;上述 14株菌进行全菌DNA打点杂交试验 ,均与irp2和 fyuA探针杂交 ;选择上述 3株菌中的 1株 ,对其整合酶基因的PCR产物测序 ,并与鼠疫耶尔森菌强毒力岛的整合酶基因序列比较 ,发现该整合酶基因于 5’端缺失了 347bp的片段。 结论 14 %肠产毒性大肠杆菌携带的耶尔森菌强毒力岛 ,且均插入在天冬酰胺转运RNA位点处 ;部分菌株所携带的耶尔森菌强毒力岛的整合酶基因发生了缺失。

Aim To detect Yersinia high pathogenicity island(HPI) and its insertion site in enterotoxigenic E.coli(ETEC) strains isolated from China Methods Polymerase chain reaction(PCR),DNA dot hybridization and nucleotide sequence analysis Results Eight genes within Yersinia HPI were amplified in 13 ETEC strains ,and the lengths of these PCR products were the same as we expected except int genes in 3 ETEC strains But asnT tRNA genes were not amplified in any of the above strains For the PCR positive strains ,DNA dot hybridization with probes for irp2 and fyuA genes were also positive The int gene PCR product amplified from one of the three ETEC strains was sequenced,and then sequence analysis was done A 357bp deletion at the 5'end of the int gene was shown Conclusion 14% of the ETEC strains in China carry Yersinia HPI which are all inserted at asnT tRNA locus Deletions of int occur in some ETEC strains.