PRRSV安徽分离株NSP2和ORF7基因的克隆与序列分析

Cloning and Sequence Analyses of the NSP2 and ORF7 Genes of PRRSV Strains in Anhui Province

2008年从安徽两个发病猪场采集疑似猪繁殖与呼吸综合征病料,在Marc-145细胞上盲传4代～5代,发现明显细胞病变,各分离到1株猪繁殖与呼吸综合征病毒(HS08株和ZJ08株)。用RT-PCR扩增这两个分离毒株的NSP2和ORF7基因,进行克隆和序列分析。结果表明,这两个分离毒株核苷酸同源性高于99.0%;在NSP2基因上,这两个分离毒株均发生30个氨基酸的不连续缺失,它们与CH-1a株之间核苷酸同源性分别为80.7%和80.2%;在ORF7基因上,与2007年国内高致病性猪蓝耳病毒株HuN4核苷酸同源性较高,分别为98.4%和99.5%,且ORF7基因均存在K46→R46,H109→Q109,V117→A117氨基酸突变。这些信息显示这两个安徽分离株属美洲型毒株,具有高致病性特征,与国内高致病性毒株位于同一基因群。

Samples were collected from two farms in Anhui province with suspected clinical signs of porcine reproductive and respiratory syndrome in 2008,and two porcine reproductive and respiratory syndrome virus isolates（HS08 and ZJ08） were isolated after 4-5 passages in Marc-145 cells.The NSP2 and ORF7 genes of the isolates were amplified using RT-PCR which was followed with cloning and sequencing.The two isolates were similar to each other（nucleotide homology 99.0%）,and they contained a discontinous 30 amino acid deletion in the NSP2 gene.The two isolates had 80.3% and 80.2% nucleotide homology with strains CH-1a,respectively,in the NSP2 gene.They had 98.4% and 99.5% nucleotide homology with the highly pathogenic strain HuN4 isolated in 2007 in the ORF7 gene,and they had mutations of K46→R46,H109→Q109,V117→A117 in the ORF7 gene.Phylogenetic analysis also revealed that the two isolates belonged to the cluster of highly pathogenic strains emerging in China in recent years.