猪繁殖与呼吸综合征病毒河南分离株ORF5基因的克隆与变异分析

Variation analysis of the ORF5 gene of porcine reproductive and respiratory syndrome virus(PRRSV)of Henan isolates

从河南郑州、新乡、周口不同地区猪场的急性病猪中分离到3株猪繁殖与呼吸综合征病毒(Porcine reproduc-tive and respiratory syndrome virus,PRRSV),分别命名为PRRSV Hn-1/06、PRRSV Hn-2/06和PRRSV Hn-3/06,细胞中和试验证实其血清型与美洲型一致。利用RT-PCR方法克隆了它们的ORF5基因,并对其基因序列和推导的氨基酸序列与7个不同来源的PRRSV毒株进行了同源性和亲缘关系比较分析,结果表明,3个分离株之间的ORF5基因及其推导的氨基酸均同源性均大于95.5%;与VR-2332标准北美洲株和疫苗株RespPRRS MLV间的同源性均低于与中国CH-1a毒株,而与流行的欧洲株间的同源性均低于54.5%。同时对推导氨基酸序列与6个北美洲型PRRSV株进行变异分析比较,证实其推导氨基酸序列发生了变异,特别是中和位点处第39位明显不同,表明河南省流行的PRRSV为北美洲型的变异株。

Three porcine reproductive respiratory syndrome （PRRSV） isolates（Hn-1/06 Hn-2/06 and Hn-3/ 06）were obtained from Henan province＇s pig farms. Their complete ORF5 genes were amplified by RT-OCR. All of the ORF5 genes of these PRRSV isolates were proved to be 603 bp. Identity and variation analysis of ORF5 gene and the deduced amino acid of these isolates with the other seven published PRRSV isolates from different source showed that the ORF5 gene and amino acid of these Henan isolates share more than 95.5% identity. Between these Henan isolates and the other America isolates,the identity ranged from 86.1% to 98.0% and 86.0% to 98.5% respectively,but the Henan isolates and LV merely share less than 54.5% identity. Further comparision of the deduced amino acid sequence of Henan isolates with other America isolates indicated that some sites of GP5 have taken into mutation, especially,the 39th deduced amino acid which locates at the neutralizating site of Henan isolates differ from other America isolates,indicating that the PRRSV isolates from herds experiencing acute PRRS outbreak in Henan would be the mutant isolates of America genotype.