大鲵肺肾囊肿的病原学研究

Pathogeny of Disease Characterized by the Cysts of Lung and Kidney of Chinese Giant Salamander(Andrias davidianus)

为查明2010年以来陕西省养殖大鲵发病导致肺脏、肾脏囊肿的病原,在无菌条件下从发病大鲵内脏器官分离致病菌,结果从肝脏中分离到一株弗氏柠檬酸杆菌(Citrobacter freundii),从肺脏、肾脏中未分离到致病菌。病理组织学观察结果显示,病鲵的肺泡、肾小管等上皮细胞变性、坏死,肝细胞广泛性空泡变性。透射电镜观察结果表明,肺脏、肾脏存在大量聚集或分散的病毒颗粒,病毒颗粒切面呈正六边形,对角直径约150nm,形态与虹彩病毒相似。根据已知虹彩病毒主要衣壳蛋白基因序列设计特异引物,提取病鲵的肝脏、肺脏、肾脏组织的DNA进行PCR扩增,将扩增片段进行序列测定与分析,结果表明该序列和推导的氨基酸序列与已报道的大鲵虹彩病毒(CGSIV)主要衣壳蛋白基因的核苷酸序列和氨基酸序列的同源性均为99%。综合试验结果判定引起病鲵肺脏、肾脏囊肿的病原是大鲵虹彩病毒。

This study was conducted to identify the pathogeny of a serious infectious disease characterized by the cysts of lung and kidney of Chinese giant salamander（Andrias davidianus ）,which began to break out in cultured Chinese giant salamander in the southern area of Shaanxi province,China since 2010.A strain of Citrobacter freundii was isolated from the liver of the sicked giant salamander,while no patho-genic bacterium in the lung and kidney.Transmission electron microscopy of the focus lung and kidney re-vealed numerous icosahedral virion with envelope and no bacterium.The diameter of the virion was about 150 nm.According to known mcp gene sequences of iridovirus,specific primers were designed to amplify the mcp gene of the current virus.Liver,lung and kidney DNA were extracted as PCR templates.PCR products were sequenced and the sequences of corresponding amino acids were predicted.Then comparative analysis of the nucleotide and amino acid sequences was performed with the GenBank databases using Blast database network service.The results showed that the nucleptide sequence and the amnio acid sequence from infected giant salamander shared high identity with homologous 99.0% of Chinese giant salamander iridovirus（CGSIV）.Transmission electron microscopy and mcp gene sequence of the virus indicated that the pathogen of the cysts of lung and kidney of sicked giant salamander is Chinese giant salamander iri-dovirus.