Molecular surveillance of Cyprinid herpesvirus 2 in goldfish cultured in China | 金鱼鲤疱疹病毒Ⅱ型的分子诊断

Chinese. 针对国内市场上流通的金鱼，开展CyHV-2的流行病学调查，并比较CyHV-2不同分离株的分子特征。结果显示：无明显临床症状的金鱼带毒率较高（13．89％），表明我国已有CyHV-2的分布。分子生物学研究显示，我国金鱼和异育银鲫来源的CyHV-2编码的解旋酶基因部分序列一致，表明异育银鲫来源的CyHV-2和金鱼来源的CyHV-2极可能为同一种病毒。同日本分离株（H．Fukuda）比较，我国金鱼来源的CyHV-2编码的DNA聚合酶基因片段序列同该毒株完全一致，但两者编码的衣壳体间三联蛋白和解旋酶各有1～2个氨基酸的差异，表明我国分布的CyHV-2同H．Fukuda毒株高度相似，但存在一定的差异。

English. Originally described from Japan, Cyprinid herpesvirus 2 （CyHV-2） was present in at least five other countries and probably has a global distribution in goldfish （Carassius auratus）. Up to now, CyHV-2 has drawn little attention and is rarely reported in China. Recently, silver prussian carp （Carassius auratus gibelio） farmed in Yancheng,Jiangsu Province,was reported by news to be infected by CyHV-2 and caused heavy economic losses. But little was known about the ways of virus transmission, potential reservoirs and sources of infection for this newly emerged virus. Goldfish can be a source of infection by carrying CyHV-2 but showing no clinical symptom. To understand the epidemiology of CyHV-2 in China, healthy goldfish from markets in different districts were tested for CyHV-2 by degen- erate polymerase chain reaction of the viral polymerase gene followed by sequencing. Results demonstrated that CyHV-2 has a wide geographic distribution in China. Molecular study indicated that the se- quences of DNA polymerase encoded by CyHV-2 isolated from goldfish in China were identical with the published sequence for CyHV-2. The helicase sequences of CyHV-2 from goldfish were also partially i- dentical with those from silver prussian carp cultured in China, suggesting that the virus carried by gold- fish and silver prussian carp were the same. Between the isolates from goldfish and H. Fukuda from Ja- pan, there was only one or two residues difference in the amino acid sequence of helicase or intercapsom- eric triplex protein, suggesting that the two isolates of CyHV-2 were highly similar,but not the same.