猪繁殖与呼吸综合征病毒CH-1R株致弱过程中ORF5基因遗传变异分析

Genetic variation of the ORF5 gene of porcine reproductive and respiratory syndrome virus CH-1R strain during the process of attenuation

将猪繁殖与呼吸综合征病毒CH-1a株在Marc-145细胞上传代,用85代(S85)病毒对35日龄的仔猪进行人工感染试验,证实该毒株已经被致弱,将其命名为CH-1R株。利用RT-PCR扩增10个不同代次的CH-1a株和CH-1R株病毒的ORF5基因,并与9株参考毒株进行RFLP分析,发现了一个特异性的内切酶酶切位点-TspEⅠ。根据该酶切位点,可以区分CH-1R株、CH-1a株、其它野生型毒株和参考毒株。ORF5基因的变异分析显示,该致弱毒株与CH-1a株以及其它8株参考毒株存在着差异,并且它们的氨基酸同源性在88.5%～97.0%之间。系统进化树研究表明该弱毒株仍属于CH-1a亚支。

An attenuated porcine reproductive and respiratory syndrome virus （PRRSV） CH-1a strain, designated CH-1 R, was obtained at 85th generation of continuous passages of the virus in Marc-145 cell line and confirmed by infecting the 35-day-old piglets. The ORF5 genes were PCR amplified from 10 different generations of the CH-1a strain and CH-1R strain and used for RFLP analysis. The results showed that the attenuated strains could be differentiated from the CH-1R, CH-1a, other isolates and the reference strains by RFLP at TspE I site. Sequence analysis showed that the ORF5 genes of the attenuated strain shared 88.5 % -97.0 % amino acid homology with CH-1a strain and other 8 reference PRRSV strains. Phylogenetic analysis showed that the attenuated strain belonged to the CH-1 a subgroup of IBDV.