大口黑鲈鱼种弹状病毒病的诊断

Diagnosis of rhabdovirus disease in juvenile largemouth bass Micropterus salmonides

对广东佛山一突发批量急性死亡现象的大口黑鲈Micropterus salmoides养殖池塘中的患病大口黑鲈鱼种进行了研究。结果表明:濒死的大口黑鲈在水面漫游,烂身、烂鳍,停止摄食,严重者体色发黑;解剖病鱼鳃有少量出血点,肝脏严重肿大、充血,脾脏肿大,胃肠空虚,肾脏肿大;流行病学调查发现,该病具有明显的传染性;从病鱼肝脏、脾脏和肾脏中未分离到致病菌,也未检测到大量寄生虫;组织病理切片观察发现,肝脏、脾脏和肾脏均呈弥漫性坏死;参考Gen Bank中弹状病毒的基因序列,设计并合成检测引物,以从自然发病鱼提取的DNA作为模板,检测结果显示,病鱼均能扩增出与预期大小片段相符的特异性产物;经过克隆测序比对显示,扩增条带的基因序列与杂交鳢弹状病毒(HSHV)、鳜鱼弹状病毒(SCRV)核苷酸序列同源性分别为96.9%、95.3%。因此,初步诊断引起大口黑鲈鱼种急性死亡的病原为弹状病毒。

Diagnosis of acute mortality was investigated in cultured juvenile largemouth bass Micropterus salmonides collected in Foshan, Guangdong Province. The morbid largemouth bass swam on the water surface, had blacken and rotten skin, and fins, and was devoid of food. The postmortem examination revealed that the sick fish had hemorrhagic gills, swollen liver, spleen and kidney, reddish intestine and empting stomach. Epidemiological survey indicated that no pathogenic bacteria and parasites were found in the organs including liver, spleen and kidney, the disease being obvious infectious. The diffused necrosis was histologically observed in liver, spleen and kidney. The specific products with predicted size were obtained in the diseased fish by primers designed according to the sequence of GenBank. Comparative analysis of nucleotide sequences in the GenBank databases using Blast database network service showed that the putative gene products from the infected largemouth bass shared high homologous identity of 96 . 9% with hybrid snakehead rhabdovirus （ HSHV ） and 95 . 3% with Siniperca chuatsi rhabdovirus （ SCRV） , indicating that the mortality of largemouth bass is caused by rhabdoviruses.