贵州省PRRSV分离株Nsp2基因的克隆及序列分析

Cloning and sequence analysis of the Nsp2 gene of porcine reproductive and respiratory syndrome virus isolated in Guizhou area

为了解贵州省猪繁殖与呼吸综合征病毒(PRRSV)分离株的遗传变异情况和分子流行病学背景,本研究收集了2007年以来贵州省不同地区的12株PRRSV,并对其Nsp2基因进行序列测定与遗传变异分析。结果表明,该12株PRRSV均与我国2006年以来流行的高致病性PRRSV(HP-PRRSV)位于进化树的同一分支中。8株PRRSV的Nsp2蛋白存在第481位和533位～561位共30个氨基酸的不连续缺失,这与以往报道的HP-PRRSV的缺失特征相同;另外4株PRRSV缺失扩大,其中的3株在第481位氨基酸的两翼又缺失了29个氨基酸,即471位～500位氨基酸缺失;另外1株除第481位和533位～561位氨基酸缺失外,在第394位缺失1个氨基酸。这些新缺失毒株的出现,显示HP-PRRSV可能出现了新的变异走向。为深入研究该病毒株的遗传与变异及其与生物学特性的关系奠定了基础。

To investigate the genetic diversity and molecular epidemiology of porcine reproductive and respiratory syndrome virus（PRRSV） in Guizhou area,the DNA fragments encoding partial Nsp2 of PRRSV isolates from Guizhou were amplified by RT-PCR and sequenced.All 12 PRRSV isolates were classified into the same clade together with the previously reported highly pathogenic PRRSV（HP-PRRSV）.Eight of the isolates had 2 discontinuous deletions（aa 481 and aa 533 to aa 561） in Nsp2 protein that showed a typical structure as previously reported for HP-PRRSV.Other 4 isolates had further deletions,of which 3 isolates were found a deletion at aa 471 to aa 500 in Nsp2 protein,and one amino acid deletion at the position of aa 394 in another isolate.The emergence of these new isolates indicated that the HP-PRRSV may evolve towards to a new trend.