PRRSV分离株Nsp2基因和ORF5基因的遗传变异分析

为了解山东省PRRSV流行毒株的遗传变异情况和分子流行病学背景,对2007~2009年分离到的14株山东省内的PRRSV流行毒株进行了Nsp2和ORF5基因序列的测定和分析。结果显示,与参考毒株JXA1相比,14株PRRSV Nsp2与ORF5基因的核苷酸同源性分别达到96.1%~99.8%和98.0%~99.8%,氨基酸序列同源性分别达到92.9%~100%和97.5%~99.5%。序列分析结果表明,14株毒株在Nsp2蛋白内部均存在编码30个氨基酸的碱基对的不连续缺失;ORF5基因编码的GP5蛋白不存在缺失,但存在点突变。遗传进化分析表明,07年分离毒株JQ与参考毒株JXA1亲缘关系很近;09年分离的12株PRRSV,2株仍与国内2006~2007年间的分离株在同一分支,9株已经处在不同分支,1株单独处在一个分支。2007~2009年山东地区流行的PRRSV分离株具有年度特征,无明显的地域特征。

Genetic Variations of Nsp2 Gene and ORF5 Gene of Porcine Reproductive and Respiratory Syndrome Virus Isolates

To fully understand the knowledge of highly pathogenic porcine reproductive and respiratory syndrome（PRRSV） molecular epidemiology and genetic variation in Shandong area,a total of 14 PRRSV isolates were isolated in 2007~2009,and Nsp2 gene and ORF5 gene of these isolates were amplified by RT-PCR and sequenced.Comparing with JXA1 strain,Nsp2 gene shared 96.1%～99.8% of nucleotide homologies and 92.9%~100% of the deduced amino acid homologies,while the ORF5 gene shared 98.0%~99.8% of nucleotide homologies and 97.5%~99.5% of the deduced amino acid homologies.Sequence results showed that all the 14 PRRSV isolates had discontinuous 30 amino acids deletions in Nsp2;the GP5 protein encoded by ORF5 gene had a few mutation but no deletion.The phylogenetic tree revealed JQ strain isolated in 2007 had closer relationship with JXA1 strain.Among the 12 PRRSV strains isolated in 2009,two strains still locate in the same branch with the domestic strains isolated between 2006 and 2007,nine strains constitute an independent branch,and 1 strain（DLS-1） forms in a separate branch,indicating that those PRRSV isolates have no obvious geographical characteristics but have an annual feature in Shandong area.