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

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

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 320nt;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。

In order to monitor the variation of highly pathogenic porcine reproductive and respira- tory 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 nucleo- tides, 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, re- spectively. 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 patho- genic PRRSV have occurred during its prevailing. Our study provides valuable genomic data for monitoring and analyzing genetic variation and evolution of highly pathogenic PRRSV.