西藏牦牛源肠出血性大肠杆菌毒力基因检测与进化分析

Virulence gene detection and phylogenetic analysis of enterohemorrhagic Escherichia coli from yak in Tibet

为调查西藏地区牦牛源肠出血性大肠杆菌的流行情况,利用PCR检测和生物进化分析方法,对西藏林芝、拉萨不同地、市149株牦牛源大肠杆菌的肠出血性大肠杆菌相关毒力基因进行了研究。结果表明:牦牛源肠出血性大肠杆菌6对毒力基因中,只检出ehxA基因,检出率为9.40%;对检测到的14株牦牛源肠出血性大肠杆菌进行克隆测序,经系统发育分析发现牦牛源肠出血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99%。因此,西藏牦牛源肠出血性大肠杆菌基因确实存在,其毒力基因主要为ehxA基因;西藏林芝、阿里、日喀则、昌都均有分布,拉萨、山南和那曲地区未检出,应引起重视。西藏地区要根据各地实际情况需要加强监测肠出血性大肠杆菌引起的腹泻,建立流行毒株预警机制并合理用药。

In order to investigate the epidemic situation of intestinal haemorrhagic Escherichia coli from Yak in Tibet area,the virulence genes of 149 of enterohemorrhagic E.coli strains from yak in Linzhi and Lhasa were studied by using PCR detection and phylogenetic analysis.The results showed:The ehxA gene was detected among the 6 pairs enterohemorrhagic E.coli virulence genes originated in yak and the detection rate was 9.40.%.Fourteen strains were then cloned and sequenced by phylogenetic analysis.It was found that enterohemorrhagic E.coli strains were of99.9% homology,and were 99.0% homology to other strains recorded in GenBank.These results indicated that the Tibetan exist enterohemorrhagic E.coli gene in yak,the main virulence gene was ehxA gene.Linzhi,Ali,Shigatse and Changdu in Tibet were the distribution areas.The enterohemorrhagic E.coli gene was not detected in Lhasa,Shannan and Nagqu.This study indicated that the survey for diarrhea caused by EHEC should be strengthened according to the actual situation.Early pandemic strain warning mechanism should then be established and the drug should be used rationally.