利用PCR法鉴定产SLT-IIe大肠杆菌

Detection of SLT- Ⅱe producing Escherichia ccoli by Ploymerase Chain Reaction

类志贺氏菌毒素Ⅱ型变异体（ Ｓｈｉｇａｌｉｋｅ Ｔｏｘｉｎ Ⅱ Ｖａｒｉａｎｔ， Ｓ Ｌ ＴⅡｖ ｏｒ Ｓ Ｌ ＴⅡｅ），是仔猪水肿病的主要致病因子。根据 Ｓ Ｌ ＴⅡｅ 基因序列，合成一对针对 Ｓ Ｌ ＴⅡｅ 操纵子基因保守区的寡核苷酸引物，建立了聚合酶链式反应（ Ｐ Ｃ Ｒ）扩增方法。通过对产 Ｓ Ｌ ＴⅡｅ 毒素大肠杆菌菌株 Ｔ Ｂ１、产 Ｓ Ｌ ＴⅡ毒素大肠杆菌菌株 ９３３ Ｗ 和产 Ｓ Ｌ ＴⅠ毒素大肠杆菌菌株 Ｈ３０ 的试验，结果表明用所设计的引物建立的 Ｐ Ｃ Ｒ方法可特异性鉴定产 Ｓ Ｌ ＴⅡｅ 大肠杆菌。用此法对本实验室从患水肿病仔猪肠道分离的 １５ 株大肠杆菌进行了鉴定，结果可从 １５ 个菌株的 １２ 株中扩增到 Ｓ Ｌ ＴⅡｅ 的特异性保守序列基因片段，而其它菌株未见此保守序列的基因片段。

Shiga like Toxin ⅡVariant(SLT Ⅱv or SLT Ⅱe)have been implicated as possible virulence factors in the pathogenesis of edema disease of swine.A set of synthetic oligonucleotide primers derived from conservative sequences of the SLT Ⅱe operator genes were used in a polymerase chain reaction(PCR)amplification procedure to detect these genes in some enteric pathogens.It was shown that the primers were able to distinguish clearly the SLT Ⅱe producing Escherichia coli.A total of 15 stains of Escherichia coli that we have isolated from some swines with edema disease were studied,and 12 of the 15 strains were found to be the SLT Ⅱe producing Escherichia coli.