2017年广东省首株欧洲型猪繁殖与呼吸综合征病毒的分离鉴定及其全基因组特征分析

Isolation,identification and complete genomic characterization analysis of the first European genotype PRRSV in Guangdong Province in 2017

猪繁殖与呼吸综合征病毒(porcine reproductive and respiratory syndrome virus,PRRSV)分为两大基因型:欧洲型(基因Ⅰ型)和北美洲型(基因Ⅱ型),我国主要流行毒株为基因Ⅱ型,基因Ⅰ型很少被报道。本研究于2017年从广东省惠州市流产率较高的某猪场的母猪群中所采集的血样中分离到1株基因Ⅰ型PRRSV,命名为EU-GD-HD株,基因组全长为14869个核苷酸(nt),除poly(A)尾,这是基因Ⅰ型PRRSV首次在广东省被报道。与欧洲型参考毒株全基因组序列比对分析结果显示,EU-GD-HD毒株与基因Ⅰ型代表株Lelystad virus(LV)的核苷酸序列同源性为85.3%,与福建FJQEU14毒株的核苷酸序列同源性最高,为94.3%,其中GP5蛋白的氨基酸序列同源性为92.6%,且与FJQEU14毒株在Nsp2和GP3蛋白上具有相同的氨基酸缺失。全长基因组和ORF5基因遗传进化树分析显示,EU-GD-HD毒株属于基因Ⅰ型PRRSV,与福建FJQEU14毒株的亲缘关系最近。重组软件分析表明,EU-GD-HD毒株未发生重组。本研究结果表明,欧洲型毒株正在进行潜在的扩散。因此,净化欧洲型PRRSV并加以控制就显得尤为重要。

Porcine reproductive and respiratory syndrome virus(PRRSV)is divided into two major genotypes:European type(genotypeⅠ) and North American type(genotypeⅡ).The major epidemic viruses in China are genotypeⅡ,while genotype I viruses are rarely reported.In this study,one genotypeⅠPRRSV,named as EU-GD-HD strain,was isolated from a blood sample collected from the sow with clinical high abortion rate on a pig farm in Huizhou City,Guangdong Province in 2017.The full genome length was 14 869 nucleotides(nt),excluding poly(A)tails.This is the first report of a genotypeⅠPRRSV in Guangdong Province.Compared with the whole genome sequences of the European reference strains,the nucleotide homology between the EU-GD-HD strain and the genotypeⅠrepresentative strain Lelystad virus(LV) was85.3%,and hold the highest the nucleotide homology(94.3%) with the FJQEU14 strain from the Fujian Province.The EU-GD-HD strain shared 92.6% amino acid homology of the GP5 protein with FJQEU14 strain,and the same amino acids deletion was found in the Nsp2 and GP3 proteins with the FJQEU14 strain.Based on full-length genome and ORF5 gene phylogenetic tree analysis showed that the EU-GD-HD strain belonged to genotype I PRRSV and was closely related to the FJQEU14 strain.Analysis of recombinant software showed that gene recombination didn’t occur in the EU-GD-HD strain.The results of the study indicated that European strains are potentially spreading.Therefore,it is particularly important to purify and control European PRRSV.