摘要：
To better understand the genetic diversity of porcine reproductive and respiratory syndrome virus (PRRSV) in Guangxi province,the Nsp2 and ORF5 genes were amplified from clinical samples in Guangxi from 2014 to 2016 and the gene sequences were analyzed.The results showed that all the acquired 34 Nsp2 and 45 ORF5 gene sequences belonged to North American genotype PRRSV (NA-PRRSV).Sequence analysis revealed that the homology of the nucleotide of Nsp2 genes was 91.8%-100%,and they shared 81.3%-84.3%,88.9%-92.1%,94.3%-99.3%,73.5%-75.1% identities with NA-PRRSV strain VR-2332,Ch-1a,JXA1 and NADC30,respectively;but shared only 51.5%-53.2% identity with European genotype PRRSV (EU-PRRSV) strain LV.The homology of the nucleotide of ORF5 genes was 91.8%-100%,and they shared 83.7%-99.5%,85%-95%,83.8%-99.7%,83.2%-86.4% identities with NA-PRRSV strain VR-2332,Ch-1a,JXA1 and NADC30,respectively;but shared only 62.4%-64.5% identity with EU-PRRSV strain LV.The phylogenetic analysis showed that all PRRSV isolates were divided into four subgroups based on the deduced amino acid sequences of Nsp2 and ORF5 genes,and most isolates from Guangxi belonged to subgroup IV which was represented by JXA1 strain.The results indicated that the highly pathogenic PRRSV (HP-PRRSV) represented by JXA1 strain has become the dominant strain in Guangxi,and there exists genetic diversity among Nsp2 and ORF5 genes of isolated strains,while EU-PRRSV and NADC30-like strain of NA-PRRSV have not yet been found.%为了解广西地区猪繁殖与呼吸综合征病毒(PRRSV)流行毒株的遗传进化情况,对2014年-2016年来自广西各地的部分PRRSV阳性病料进行Nsp2和ORF5基因的扩增和测序分析.结果获得34个Nsp2基因序列和45个ORF5基因序列,均属于美洲型毒株.Nsp2基因间核苷酸序列的同源性为91.8％~100％,与PRRSV美洲型毒株VR-2332、CH-1a、JXA1及NADC30株核苷酸序列的同源性分别为81.3％~84.3％、88.9％~92.1％、94.3％~99.3％和73.5％~75.1％,而与PRRSV欧洲型毒株LV株核苷酸序列的同源性为51.5％~53.2％.ORF5基因间核苷酸序列的同源性为82.8％~100％,与PRRSV美洲型毒株VR-2332、CH-1a、JXA1及NADC30株核苷酸序列的同源性分别为83.7％~99.5％、85％~95％、83.8％~99.7％和83.2％~86.4％,而与PRRSV欧洲型毒株LV株核苷酸序列的同源性为62.4％~64.5％.基于Nsp2和ORF5基因推导的氨基酸序列绘制的遗传进化树中,广西地区的毒株主要分布在以JXA1为代表的Ⅳ亚群.表明当前广西PRRSV流行毒株以JXA1株为代表的高致病性美洲型毒株为主,各毒株Nsp2和ORF5基因序列存在一定的差异,尚未发现欧洲型毒株和美洲型NADC30类毒株.
