两株高致病性PRRSV河南分离株ORF5基因克隆及遗传变异分析

Genetic Analysis of the ORF5 Genes of Two Henan Highly Pathogenic PRRSV Isolates

从河南信阳和新乡两地区猪场疑似猪繁殖与呼吸综合征病料中分离出能引起Marc145细胞病变的病毒,命名为HN1和HN2。采用RT-PCR方法从分离的2株PRRSV中均分别扩增出ORF5基因,并将其克隆、测序。用DNAStar软件分析所测序列,并与北美洲型VR-2332株及国内分离株进行核苷酸和推导的氨基酸同源性比较,绘制系统进化树,结果表明,ORF 5核苷酸与北美洲型的同源性为81.2%～99.1%,与欧洲型Lv株的同源性分别为35.9%和35.3%,推导氨基酸与北美洲型的同源性为84.5%～99.5%,与欧洲型Lv株的同源性分别为46.0%和45.5%。证明新分离到的PRRSV毒株仍属北美洲型。与国内分离的高致病性PRRSV毒株JXA1、HUB1、JX0612、GDZC1、ZQ、SX-1、HB1、HEB1、Hnyz核苷酸同源性达96.5%～99.1%,氨基酸同源性为96.0%～99.5%。分析结果表明,所获得的2个毒株GP5蛋白氨基酸序列中的抗原表位已经发生变异。

Two strains of virus causing CPE of Marc-145 cells were isolated from the tissues of dead pigs,which collected from Xinyang and Xinxiang areas of Henan province and primarily diagnosed as swine porcine reproductive and respiratory syndrome （PRRS）. These two strains were named as HN1 and HN2, and the ORF5 genes of PRRSV were cloned and sequenced,respectively. Compared with those of VR-2332,Lv and other strains isolated in China, the ORE5 genes of HN1 and HN2 strains shared 81.2% to 99.1% nucleotide homologies with the North American type, and shared 35.9% and 35.3% with European Lv strain. The deduced amino acid homology shared 84.5 % to 99.5 % with North American type and shared 46.0 % and 45.5% with European Lv strain. This indicated that the isolated strains were related to the genotype of North American PRRSV. The nucleotide sequence homologies were 96.5 % to 99.1% and amino acid homologies were 96. 0% to 99. 5% comparing with the highly pathogenic PRRSV JXA1, HUB1,JX0612, GDZC1 ,ZQ,SX- 1, HB1, HEB1 ,and Hnyz strains. The results showed that the antigen epitope of GP5 proteins of HN1 and HN2 strains have mutated.