河北省规模猪场猪生殖与呼吸综合征病毒的变异分析

Variation analysis of porcine reproductive and respiratory syndrome virus strains from intensive pig farms in Hebei Province

为了解河北省规模猪场猪生殖与呼吸综合征病毒（PRRSV）的变异情况,采用RT-PCR方法对2004-2007年采集的12个典型发病场的病料样本进行了PRRSVNsp2和ORF5基因扩增、克隆和测序,利用DNAStar和DNAMAN软件对所测序列进行了分析。结果显示,扩增的ORF5基因氨基酸序列同源性为98.7%-100%,与美洲型和欧洲型PRRSV参考株的同源性分别为88.9%-100%和62.9%-63.5%;扩增的Nsp2基因氨基酸序列同源性为82.8%-100%,与参考毒株的同源性为76.5%-100%;从2006-2007年的样本中扩增的6个PRRSVNsp2基因均在第481位和533-561位共缺失30个氨基酸;系统进化树分析表明,这6个样本株均属于美洲型,分属于2个基因亚群,其中HB0503株与BJ4、NJ1、HN1、LP1和VR-2332遗传关系较近,其他株与JXA1、SX和BJ株遗传关系较近。结果表明,危害河北省规模猪场的PRRSV已经发生了较大的变异,其中2004-2005年的样本株属低致病性PRRSV毒株,而2006-2007年的样本株属高致病性PRRSV毒株。

To investigate the variation of porcine reproductive and respiratory syndrome virus （PRRSV） in Hebei Province, samples collected from 12 intensive pig farms suffered with PRRSV from 2004 to 2007 were tested by using RT PCR. The ORF5 and Nsp2 genes were subjected to PCR amplification,cloning and sequencing by using DNAStar and DNAMAN softwares. The results showed that the amplified ORF5 genes shared from 98. 7% to 100% amino acid homology among them, and shared from 88.9% to 100% and from 62.9% to 63.5% amino acid homology with reference strains of North American and Europe genotypes. The amplified Nsp2 genes shared from 82.8% to 100% amino acid homology among them, and shared from 76. 5% to 100% amino acid homology with reference strains, respectively. The 6 Nsp2 genes amplified from samples collected from 2006 to 2007 exhibited 30 amino acid deletion（amino acid 482 and amino acid 533 to 561）. Phylogenetic analyses showed the Hebei PRRSVs represented North American genotype and belonged to 2 different subgroups,of which, HB0503 was closely related to BJ4,NJ1,HN1,LP1 and VR 2332 strains, and the others were closely related to JXA1,SX and BJ strains. The results suggested that the PRRSVs from the samples collected from 2004 to 2005 were low pathogenic,and the samples collected from 2006 to 2007 were highly pathogenic.