浙江省猪繁殖与呼吸综合征病毒ORF5基因的遗传变异分析

为了解2014-2016年浙江地区猪繁殖与呼吸综合征病毒（porcine reproductive and respiratory syndrome virus，PRRSV）ORF5基因变异情况，试验通过RT-PCR方法对从浙江省各地区采集的PRRSV阳性病料进行ORF5基因扩增，应用DNAStar和Mega 5.1软件对所测序列进行同源性和遗传变异分析。结果显示，54株2014-2016年浙江分离株ORF5序列之间核苷酸和氨基酸序列同源性分别为83.1%~100%和80.6%~100%，与经典株VR2332核苷酸和氨基酸序列同源性分别为83.8%~90.4%和81.6%~90.0%，与高致病PRRSV毒株JXA1核苷酸和氨基酸序列同源性分别为83.5%~99.5%和83.1%~99.0%。系统进化分析表明，54个毒株均为美洲型毒株，属于Ⅰ、Ⅲ、Ⅳ 3个不同的基因亚型，其中基因亚型Ⅲ和Ⅳ毒株是浙江省近年来新出现的毒株。氨基酸序列分析结果显示，54个毒株在GP5蛋白的信号肽区域、非中和抗体表位的氨基酸序列变异较大，而在中和表位氨基酸序列变异较小。本研究结果表明，浙江地区PRRSV流行出现了新形势，多种基因亚型共同存在，其中以基因亚型Ⅰ毒株为主。

Genetic Variation Analysis of ORF5 Gene of Porcine Reproductive and Respiratory Syndrome Virus in Zhejiang Province

To assess the genetic diversity of ORF5 gene of porcine reproductive and respiratory syndrome virus (PRRSV) in Zhejiang province from 2014 to 2016,ORF5 gene was amplified and sequenced in the PRRSV positive samples which were collected from different places of Zhejiang province.The homologous analysis and genetic analysis were conducted by DNAStar and Mega 5.1 softwares.Homologous analysis showed that ORF5 gene of 54 PRRSV strains shared 83.1% to 100% nucleotide homology and 80.6% to 100% amino acid homology.ORF5 gene of 54 PRRSV strains shared 83.8% to 90.4% nucleotide homology and 81.6% to 90.0% amino acid homology with classical strain VR2332.ORF5 gene of 54 PRRSV strains shared 83.5% to 99.5% nucleotide homology and 83.1% to 99.0% amino acid homology with virulent strain JXA1.The phylogenetic tree based on sequences of ORF5 gene suggested the 54 strains could be classified in subgenotypes Ⅰ,Ⅲ and Ⅳ,among them,subgenotypes Ⅲ and Ⅳ were new strains in Zhejiang province in recent years.Compared with antigen epitopes,54 PRRSV strains had higher variation in the signal epitope and non-neutralizing antigen epitopes,and had little variation in neutralizing epitope.The results indicated that four subtypes of PRRSV existed in Zhejiang province,but mainly prevailing the subgenotype Ⅰ PRRSV strain.