中文摘要：

以PRRSVGD-2007株为材料，在自然条件和抗体压力下连续传至40代后，分别命名为PRRSV—GD—f40和PRRSV—GDAb—f40，进行RT—PCR，扩增Nsp2基因部分序列和GP5基因全长，克隆并测序。应用序列分析软件将测序结果和已经发表的PRRSV毒株进行比对，结果显示：Nsp2基因扩增片段大小均为796bp，自然传代和抗体压力下传代后的新毒株和母源毒株的相似性分别为98．0％和97．9％；扩增的GP5基因大小为603bp，编码200个氨基酸，和母源毒株的相似性分别为99．2％和98．8％。

英文摘要：

PRRSV strain GD was continuously propagated in Marc-145 cells for 40 passages without PRRSV antibody or with PRRSV antibody and the viruses after passages were named RRRSV-GD-f40 or RRRSV-GDAb-f40 respectively. Nsp2 and GP5 genes were cloned and sequenced. Comparison results showed that the amplification fragment of Nsp2 gene of all isolates were 796 bp long and shared 98.0% or 97.9% similirities with maternal strain respectively. The GP5 genome analyses showed that their cDNAs of GP5 were 603bp long and shared 99.2% or 98.8% similirities with maternal strain respectively.