西藏牦牛源大肠杆菌分离株的致病性及遗传进化分析研究

为研究西藏牦牛源大肠杆菌的致病性及其遗传进化情况,了解其与其他动物源大肠杆菌的亲缘关系,采集西藏牦牛腹泻粪便240份,采用微生物学方法对其进行细菌的分离培养、血清型鉴定和致病性研究,并运用分子生物学方法对其进行16SrRNA鉴定、测序和系统发育分析。结果表明:获得的16株牦牛致病性大肠杆菌分离株中:3株与猪源致病性大肠杆菌亲缘关系较近;5株与禽源致病性大肠杆菌亲缘关系较近;2株与犊牛源大肠杆菌亲缘关系较近;4株与牛源大肠杆菌亲缘关系较近;1株牦牛源致病性大肠杆菌单独形成一个较远的分支;1株与痢疾杆菌和人源出血性大肠杆菌亲缘关系较近,可能成为对人类造成潜在危险的病原菌。西藏牦牛源大肠杆菌与牛源、禽源、猪源、人源大肠杆菌的之间亲缘性很近,存在跨种间传播风险。该种西藏牦牛源大肠杆菌动物致病试验表明,致死率高达95%,应引起高度重视。

Pathogenic and phylogenetic analysis on the Escherichia coli derived from Tibetan yak

In order to study the pathogenicity and phylogeny of Tibetan yak-derived Escherichia coli, and relationship with other animal sources of E. coli. A total of 240 samples of Tibetan yak diarrhea stool samples were collected and the bacteria were isolated, serotyped and pathogenic tested by microbiological methods. 16S rRNA was identified, sequenced and phylogenetically analyzed by molecular biology method. The results showed that among the 16 yak-derived pathogenic E. coli isolates:Three strains were closely phylogenic to swine-origin pathogenic E. coli. Two strains were closely phylogenic to the pathogenicity of avian pathogenic E. coli. Two strains were closely phylogenic to calf source E. coli and four strains were closely phylogenic to E. coli derived from cattle. One strain of yak pathogenic E. coli formed a distant separate branch. One yak-derived pathogenic E. coli and Shigella and human hemorrhagic E. coli were in the same phylogenetic tree and might become the potential pathogens of yak and human. There were close phylogenetic relationships among the Tibetan yak source E. coli and bovine, poultry, pig, human derived E. coli, which meant the risk of interspecies transmission. Animal experiments showed that the Yak-derived E. coli, with caused 95% mortality of the experimental animals, should be paied more attention. This study would provide references for the prevention and control of yak source E. coli disease.