According to the sequence of porcine reproductive and espiratory syndrome virus (PRRSV) VR-2332 published in GeneBank, the primers were designed to amplify the gene sequence of nonstructure protein 2(Nsp2) of PRRSV TJ and TJM strain. After amplication, clone, transformation of Nsp2 code region, the correct clones were identified. And then they were sequenced. The results showed that the length of TJ Nsp2 is 2 850 bp, and TJM Nsp2 is 2 490 bp. Furthermore, sequence analysis compared with classical virus VR-2332, the homology at the nucleotide levels between TJ, TJM and VR-2332 was found to be 83.6％ and 82.9％ respectively. Using RNAdraw, a software to analyze RNA structure, this test analyzed the Nsp2 RNA structure of PRRSV VR-2332,TJ, and TJM. The result showed the secondary structure of Nsp2 was complex. They are significantly different. The nucleotide sequence changes of PRRSV Nsp2 lead to the variation of RNA secondary structure. We presume the changes of Nsp2 might be a reason for different virulence between PRRSV VR-2332, TJ, and TJM.%参照GenBank中PRRSV VR-2332株全序列设计特异性引物,扩增高致病性猪繁殖与呼吸综合征病毒(Porcine reproductive and respiratory syndrome virus,PRRSV)TJ株和其致弱毒株TJM株非结构蛋白2(Nonstructure protein 2,Nsp2)编码区,经过基因的扩增、连接、转化、筛选阳性克隆进行核苷酸测序.结果表明,PRRSV TJ株Nsp2长2 850 bp,TJM株Nsp2长2 490 bp.通过序列比较分析,发现Nsp2编码区序列保守性差,TJ株和TJM株Nsp2与VR-2332核苷酸序列的同源性分别为83.6%和82.9%,运用RNAdraw软件对Nsp2编码区RNA的2级结构预测分析表明,分离的高致病性强毒株TJ株和细胞致弱毒株TJM株与经典毒株VR-2332有较大不同,PRRSV Nsp2的1级序列的变化导致RNA的2级结构发生构象变化,推测这可能是3个PRRSV毒株致病力不同的原因之一.
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