猪繁殖与呼吸综合征病毒WF-1株的分离鉴定及NSP2和ORF5基因的变异分析

Isolation and Sequence Analysis of NSP2 Gene and ORF5 Gene of Porcine Reproductive and Respiratory Syndrome Virus WF-1 Strain

从山东某大型猪场患"猪高热病"的病料中分离到1株病毒,该病毒可在Marc-145细胞上增殖,产生细胞病变。经RT-PCR鉴定证明,该病毒为美洲型猪繁殖与呼吸综合征病毒(PRRSV),将其命名为WF-1株。用RT-PCR法分别扩增该分离株的NSP2基因和ORF5基因,并进行核苷酸序列测定和分析。结果表明,PRRSV WF-1株的NSP2发生30个氨基酸的不连续缺失,缺失位置与PRRSV参考变异株JXA1相同;ORF5基因与JXA1、CH-1a、VR2332核苷酸同源性分别为98.0%、94.2%、86.4%,氨基酸同源性分别为97.5%、94.0%、87.5%。基因遗传进化树分析结果显示,WF-1株与2006～2008年期间分离的JXA1、SX-1等高致病性变异株的亲缘关系很近,与1996年分离的中等毒力毒株CH-1a亲缘关系较远,与VR2332、CC-1、MLV等弱毒株或疫苗株处于不同的分支。

A strain of porcine reproductive and respiratory syndrome virus（PRRSV）was isolated from a pig herd with high fever syndrome in Shandong and it was designated as WF-1 strain.The NSP2 gene and ORF5 gene of WF-1 strain were amplified by RT-PCR and sequenced thereafter.The results showed that WF-1 strain was classified into the North American genotype and it had discontinuous 30 amino acids deletions in NSP2.The ORF5 gene of WF-1 strain shared 97.5 %,94.0 % and 87.5 % in nucleotide level,and 97.5 %,94.0 %,87.5 % in amino acid level,with those of JXA1,CH-1a and VR2332,respectively.Phylogenetic tree analysis revealed that WF-1 had closer relationship with JXA1 and SX-1 strains than classical strains,such as CH-1a,HN1,VR2332,CC-1.