尖吻鲈Lates calcarifer虹彩病毒病的诊断

Diagnosis of Iridovirus Disease in Sea Bass Lates calcarifer

对广东珠海一养殖池塘中尖吻鲈Lates calcarifer的发病情况进行了调查。调查发现,病鱼体色发黑,剖检可见鳃充血发紫;空肠空胃,肠道微红,脾和肾肿大,有出血点,胆囊充盈,有胆汁渗出,肾发黑,有出血点,其他组织器官无明显变化。从病鱼的鳃、肝、肾、肌肉、肠道,和血液中未检查到寄生虫,从肝、脾和肾中未分离到致病菌。参考世界动物卫生组织(Office International des Epi-zooties,OIE)设计引物,提取自然发病鱼各种组织的DNA作为模板,扩增出了预期大小的特异性产物。测序比对显示,扩增的条带的基因序列与真鲷虹彩病毒(Red sea bream iridovirus,RSIV)的基因序列同源性高达98.6%。病理切片显示:肝和脾出现肿大细胞。因此,引起尖吻鲈发病死亡的原因是肿大细胞病毒属虹彩病毒感染。

The diagnosis of iridovirus diseased sea bass Lares calcarifer was conducted at a farm in Zhuhai City, Guangzhou Province. The postmortem examination revealed that the sick fish had main symptoms of blacken body, the emptying stomach and reddish intes- tine, swollen spleen and kidney with hemorrhagic spots, filling gall bladder with bile leakage, and the blacken kidney No significant changes were observed in other organs of the diseased fish. Parasites were not found in gill, liver, kidney, muscle, intestine, and blood, and no pathogenic bacterium was isolated from organs including liver, spleen and kidney in the diseased fish. Primers were designed according to the sequence of Office International des Epi-zooties （OIE）, and specific products with predicted size were obtained from all diseased tissues. Sequence alignment showed that the amplification of a band gene sequence had as high as 98.6% of homology with gene sequence of red sea bream iridovirus. Histopathological observation showed there were many enlargement and necrosis cells in liver and spleen, indicating that the diseased and dead sea bass is caused by in a genus iridovirus Megalocytivirus, and characterized by swollen cells in the fish with the viral infection.