一株高致病性猪繁殖与呼吸综合征病毒变异毒株的基因组特征

为了监测我国近年来流行的高致病性猪繁殖与呼吸综合征病毒(PRRSV)的变异情况,采用RT-PCR分段扩增,对2009年从山东发病猪场分离到的1株PRRSV SD0901的全基因组进行了序列测定和分析.结果表明,不包括Poly(A)尾,该毒株的基因组全长为15 320 nt；与高致病性PRRSV毒株间的全基因组核苷酸相似性为98.6％～98.7％；该毒株基因组的Nsp2编码区除存在与高致病性毒株相同的30个氨基酸的不连续缺失外,还存在468位的氨基酸缺失和在585-586位间插入1个氨基酸,同时,该毒株的结构蛋白GP2、GP3、GP4和M编码区分别存在1个氨基酸的突变.演化分析表明,该毒株尽管与高致病性毒株属于同一亚群,但形成一个独立的小分支.由此表明,该毒株为高致病性PRRSV的变异毒株,说明我国的高致病性PRRSV在流行过程中已出现变异.笔者的研究结果为监测和分析我国的高致病性PRRSV的变异与演化提供了有价值的基因组信息数据.

Genomic Characterization of a Variant of Highly Pathogenic Porcine Reproductive and Respiratory Syndrome Virus

In order to monitor the variation of highly pathogenic porcine reproductive and respiratory virus(PRRSV) prevailing in recent years,the complete genome of a strain of PRRSV SD0901 isolated from one pig farm with clinical outbreak of PRRS was sequenced and analyzed by RT-PCR amplification.The results showed that the genome size of the virus was 15 230 nucleotides,excluding the poly(A) tail.Comparative analysis of the whole genomic sequences revealed that the virus shared 98.6%-98.7% identity with the representative strains of highly pathogenic PRRSV,and exhibited additional one amino acid deletion and insertion at the position 468 and 585-586 respectively,besides 30-amino acid deletion within its Nsp2-coding region.In addition,one amino acid variation was found in GP2,GP3,GP4 and M-coding regions of its genome,respectively.Phylogenetic analysis showed that the virus formed an individual branch although it belonged to the same subgroup as highly pathogenic PRRSV strains.These findings indicate that the virus is a variant of highly pathogenic PRRSV,implying that the variation of highly pathogenic PRRSV have occurred during its prevailing.Our study provides valuable genomic data for monitoring and analyzing genetic variation and evolution of highly pathogenic PRRSV.