西藏牦牛源大肠杆菌毒力基因检测与分型

Escherichia coli virulence gene detection and classification in Tibetan yak

为了了解西藏地区牦牛源肠产毒性大肠杆菌毒力基因分布情况,本试验对西藏林芝、拉萨等不同地、市107株牦牛源大肠杆菌进行了大肠杆菌毒力基因的PCR检测和基因分型。结果显示,利用22对肠产毒性大肠杆菌毒力基因引物进行检测,只检出STp以及CS8基因;对所检测到的16株牦牛源肠产毒性大肠杆菌进行克隆测序,经系统发育分析发现牦牛源肠产毒性大肠杆菌菌株内同源性达到99.9%左右,与GenBank中所录其他菌株的同源性达到95%~100%。按照系统发育进化分型的方法,对16株大肠杆菌中有3株属于D群,其余均属于A群。结果表明,西藏牦牛源大肠杆菌中肠产毒性大肠杆菌基因确实存在,其毒力基因主要为STp以及CS8基因;西藏林芝、拉萨、山南和日喀则均有分布,那曲和阿里地区未检出,通过对小鼠的致病性试验,致死率为95%,说明致病性很强,应引起重视。

In order to understand the distribution of Tibetan yak enterotoxigenic E. coli virulence genes,providing scientific basis for prevention and treatment. 107 yak Escherichia coli were investigate of from the different areas of Linzh, Lhasa and other city by PCR detection for genotyping of virulence genes. The results showed that using yak source 22 pairs primers of enterotoxigenic E. coli virulence genes,only detected TSp and CS8 gene. 16 detected enterotoxigenic Escherichia coli isolates were cloned and sequenced by phylogenetic analysis about 99.9 % homology, and homology of 95%-100% with other strains recorded in GenBank. According to the phylogenetic classification method,out of 16 E. coli strains,3 isolates were belong to the D group,and the rest belong to the A group. These results indicated that the Tibetan yak source enterotoxigenic E. coli strains, exist the virulence genes, mainly STp and CS8 gene,is distributing in the areas of I inzhi, Lhasa, Shan- nan and Xigaze, without Nagqu and Ngari. Through pathogenicity tests in mice, mortality was 95 %, highly pathogenic isolates.