大鲵虹彩病毒流行株的分离及其主衣壳蛋白编码基因序列比较分析

Isolation and analysis of MCP gene in giant salamander iridovirus epidemic strains

大鲵虹彩病毒（giant salamander iridovirus, GSIV）是近年中国大陆新发现的引起人工养殖大鲵（Andrias david-ianus）大规模死亡的病毒病原。为了揭示大鲵虹彩病毒流行株的基因型差异,本研究对2010-2012年采集自全国不同大鲵养殖区域的患虹彩病毒病的大鲵样本进行了分子检测、病毒分离培养以及病毒主衣壳蛋白（major capsid protein, MCP）基因测序与比对分析。结果显示,采自陕西、湖北、湖南、浙江、江西、福建等省的10个样本检测为阳性,通过细胞培养获得10株病毒流行株。对该10株流行株MCP基因的测序与比对分析发现,核苷酸序列相似性达到99.7%~100%,其推测的氨基酸序列无明显差异,证实中国大鲵虹彩病毒流行株属同一基因型。系统进化树分析结果表明,所选大鲵虹彩病毒与蛙病毒分别聚为一枝,但其亲缘关系较近。本研究结果旨为大鲵虹彩病毒病的疫苗研制及其免疫防控技术研究奠定基础。

Giant salamander iridovirus （GSIV） is a viral pathogen, recently discovered in China, that causes mass mortal-ity of farmed giant salamander （Andrias davidianus）. Our objective was to evaluate the epidemiology of the disease and document genotype differences among strains isolated during epidemics at the major giant salamander breeding areas in China between 2010 and 2012. We performed molecular detection, virus isolation and propagation, and viral titer determi-nation. Additionally, the major capsid protein （MCP） genes of the virus strains were sequenced and analyzed. The 10 sam-ples that were collected from Shaanxi, Hubei, Hunan, Zhejiang, Jiangxi, and Fujian provinces tested positive. We subse-quently obtained 10 GSIV epidemic strains by cell culture. Sequencing and comparative analysis of the MCP genes of the 10 epidemic strains revealed the nucleotide sequences had 99.7%–100%similarity and there was little difference among the deduced amino acid sequences. This suggests that all the epidemic strains are of the same genotype. The phylogenetic analysis suggested that the GSIV and frog virus strains clustered into different two branches, but the distance between branches was relatively minor. Our results provide a foundation for the development of a GSIV vaccine.