2013年-2014年江西地区PRRSV分离株NSP2及ORF5基因的遗传变异分析

为研究江西地区猪繁殖与呼吸综合征病毒(PRRSV) ORF5基因的变异情况及NSP2基因的结构特征,采用RT-PCR方法扩增了12份江西地区猪场疑似患PRRS的猪肺脏样品中的ORF5全序列和NSP2部分序列,应用DNAStar和Mega 6.0等软件对所得序列进行同源性比对及遗传变异分析。12株PRRSV ORF5核苷酸同源性为83.7%~99.8%,氨基酸同源性为82.1%~99.5%;与参考毒株JXA1、VR-2332和LV的核苷酸同源性分别为84.9%~99.7%、85.2%~91.0%和62.4%~64.8%。对阳性病料进行了NSP2基因部分序列的扩增,测序结果显示12株PRRSV均属于美洲型毒株,12株PRRSV的NSP2部分序列均存在30个氨基酸的不连续缺失,与高致病性PRRSV有相同的缺失特征。12株PRRSV的ORF5遗传进化树分析显示,10株与高致病性PRRSV处在同一进化分支,进一步说明高致病性PRRSV已成为江西地区的优势流行毒株。

Genetic Variation Analysis of NSP2 and ORF5 Genes of PRRSV Isolates in Jiangxi Province from 2013 to 2014

To study the genetic varations of ORF5 and NSP2 genes of porcine reproductive and respiratory syndrome virus (PRRSV) isolates in Jiangxi province from 2013 to 2014, the complete ORF5 gene and subsequence of NSP2 gene of PRRSV were amplified by RT-PCR from lung samples of swine in Jiangxi.Sequence comparison and genetic variation analysis were conducted by DNAStar and Mega 6.0.The results showed that the homologies of ORF5 genes among the 12 PRRSV isolates were 83.7% to 99.8% and 82.1% to 99.5% in nucleotide and amino acid sequences, respectively.Compared to the reference strains JXA1, VR-2332 and LV, the homologies were 84.9% to 99.7%, 85.2% to 91.0% and 62.4% to 64.8%, respectively.Nsp2 sequences were amplified from positive samples and compared with the other published sequences, it indicated that 12 PRRSV isolates from Jiangxi belonged to Northern American genotype, 12 isolates had 30 amino acids discontinuous deletions in NSP2 protein which showed a typical structure as previously reported for highly pathogenic PRRSV.The phylogenetic tree of ORF5 of 12 isolates indicated that 10 PRRSV isolates were in the same branch with the highly pathogenic PRRSV, which showed that the highly pathogenic PRRSV had become the dominant PRRSV epidemic strain in Jiangxi.