猪繁殖与呼吸综合征病毒国内分离经典株与变异株的全基因组序列分析

通过分段设计引物,对猪繁殖与呼吸综合征病毒(PRRSV)LX、JX株基因组进行RT-PCR扩增,对各片段cDNA进行克隆和序列测定,拼接后获得全基因组序列。结果,PRRSV LX株全基因组序列长度为15 412 bp(不包括PolyA尾),PRRSV JX株全基因组序列长度为15 320 bp(不包括PolyA尾)。序列分析表明,JX株全基因组核苷酸序列与LX株、JXA1、VR2332、CH-1a、BJ-4、LV同源性分别为91.1%、98.6%、91.0%、94.6%、90.9%、61.7%;LX株全基因组核苷酸序列与JX株、JXA1、VR2332、CH-1a、BJ-4、LV同源性分别为91.1%、89.7%、99.7%、91.5%、99.7%、62.2%。对不同分离株的5′-UTR、Nsp2进行了序列比较,并根据5′-UTR、Nsp2、ORF5的基因序列和氨基酸序列,对国内外分离株进行了系统进化分析。根据5′-UTR核苷酸序列,可将PRRSV美洲型毒株分为4个亚群,LX株和JX株分别属于经典美洲型和"高热病"变异型。根据Nsp2氨基酸序列分析了不同分离株的分子进化关系,表明依据Nsp2序列美洲型分离株可初步划分为5个亚群,JX株独立于其他毒株,独自处于一个分支。依据ORF5序列也可将美洲型分离株划分为5个亚群。本研究为探讨PRRSV的分子进化奠定了基础。

Sequence analysis on complete genome of classical and mutant strains of porcine reproductive and respiratory syndrome virus from China

The complete genomes of porcine reproductive and respiratory syndrome virus(PRRSV) strains LX and JX were cloned and sequenced.The complete genomes of LX and JX in length were 15 412 bp and 15 320 bp excluding the poly A,respectively.Compared with other reference strains,such as JXA1,VR2332,CH-1a,BJ-4 and LV,the sequence identities of PRRSV JX strain were 91.1%,98.6%,91.0%,94.6%,90.9% and 61.7%,respectively;the sequence identities of PRRSV LX strain were 91.1%,89.7%,99.7%,91.5%,99.7% and 62.2%,respectively.The comparison for the nucleotide sequences of 5-UTR,Nsp2 and ORF2-6 from different isolates showed that the maximal mutation sites were Nsp2 and ORF5 from North American strain of PRRSV.North American strain of PRRSV could be divided into four subgroups according to the nucleotide sequence of 5′-UTR,LX strain and JX strain belonged to classical American type and"hyperpyrexia disease"mutation type,respectively.On the basis of the nucleotide sequences of Nsp2 and ORF5,North American strain of PRRSV could be divided into five subgroups,and PRRSV JX strain was independent.