猪繁殖与呼吸综合征病毒CH-1R株全基因组序列测定及遗传变异分析

Sequencing analysis of full length genome of porcine reproductive and respiratory syndrome virus CH-1R strain

为了解猪繁殖与呼吸综合征的弱毒(PRRSV)株在基因组水平上的变异和分子遗传特征,本研究对致弱毒株CH-1R株进行了全基因组序列的测定。结果表明,CH-1R株基因组序列全长15424nt,具有典型的动脉炎病毒基因组结构。通过与亲本株CH-1a株序列进行比对,发现其基因组内碱基的缺失和突变主要分布在ORF1a基因的第2191位～2193位、ORF5基因的第439位、ORF6基因的第49位和ORF7基因的第28位和第139位。其中PRRSVCH-1R株的Nsp2蛋白和结构蛋白的变异相对较大,尤其是Nsp2蛋白的变异,同CH-la株相比,CH-1R株的Nsp2蛋白存在多处核苷酸的突变,其中包括连续3个核苷酸发生缺失;由结构蛋白基因推导的氨基酸序列共有17处变异,在各结构蛋白中以GP3和GP5蛋白变异较大,而高度保守的M蛋白和N蛋白,同样发生了变异,由此预测了Nsp2蛋白的R631E、GP5蛋白的L146Q、M蛋白的Q16L和N蛋白的K46N处毒力相关的氨基酸位点,推测其在毒株致弱过程中起到了重要的作用。

To study the genetic variation and molecular features of the PRRSV attenuated strain,the full length genome of attenuated PRRSV CH-1R strain was sequenced.The complete genome was 15425 nt in length.Compared with the parent strain CH-1a,several nucleotide deletions and mutations in the CH-1R strain were identified,mostly located at position 2191 to 2193 of ORF1a,103 of ORF5,49 of ORF6,28 and 139 of ORF7.The variations in the Nsp2 protein and structural protein region were significant,with numerous nucleotide mutations and three nucleotide deletions were found in the CH-1R NSP2 protein.There were 17 amino acids variations identified in the structural protein,especially GP3 and GP5 proteins.Mutation at highly conservative M protein and N protein also occurred.Based on the sequence analysis,four of virus virulent related amino acid sites were predicted,including E631 of Nsp2 protein,Q146 of GP5 protein,L16 of M protein and N46 of N protein,which was important in the attenuated process.