鸭疫里默氏菌的分离鉴定及其对SPF鸭的致病性研究

Isolation and identification of Riemerella anatipestifer and the pathogenicity to SPF duck

为研究鸭疫里默氏菌(RA)对SPF鸭的致病性,本实验室从不同省份疑似RA感染鸭场分离到4株细菌,经菌落形态观察、染色镜检、生化鉴定确定为RA。药敏试验表明这4个分离株对嗯诺沙星、氧氟沙星和先锋霉素V相对敏感,但对卡那霉素和庆大霉素均耐药。外膜蛋白A(OmpA)基因的克隆测序结果显示,4个RA分离株的ompA基因全长均为1 164 bp,编码387个氨基酸;核苷酸同源性为89%～100%。将5×108cfu的HLG1分离株经颈部皮下接种SPF鸭,病死SPF鸭的心、肝、脾、肺、脑和肾具有典型的病变。RA的分离鉴定技术为SPF鸭群RA的检测和监测以及为培育和净化SPF鸭作为RA的致病机理和疫苗研究中的实验动物模型奠定了基础。

In the present study, four bacteria were isolated from affected ducks in duck farms from Heilongjiang, Shandong, Guangdong province, respectively, and identified as Riemerella anatipestifer, designated HLG1, SD0901, SD0902 and GD0901, according its morphology, serologic test and biochemical characteristics. The four isolates were high sensitive to enrofloxacin, ofloxacin and cephalosporin V, but resistive to kanamycin and gentamycin. The cloning and sequencing of ompA genes of the isolates showed that ompA gene was 1,164 bp in length, which shared 89 % to 100 % similarity with other R.anatipestifer reference strains, Furthermore, SPF ducks were subcutaneously injected in cervical part at a dosage of 5x108 cfu of isolate HLG1 and showed the clinical signals of R.anatipestifer infection and pathological changes in heart, liver, spleen, lung, brain and kidney. The isolation and identification of R.anatipestifer from duck was contributed to diagnosis and monitoring of the diseases in SPF ducks which were used as the animal model to study on the pathogenesis and immunology.