猪繁殖与呼吸综合征病毒(PRRSV)江苏分离株NJGC ORF5基因的克隆及遗传变异分析

摘要

为了分析江苏省流行的猪繁殖与呼吸综合征病毒(PRRSV)的遗传变异特征,采用RT-PCR方法对江苏地区分离的PRRSV NJGC株的ORF5基因进行了克隆和测序,利用DNAstar软件与国内外代表性毒株进行了同源性分析与序列对比,并绘制了系统进化树.结果表明:NJGC株属于美洲型PRRSV,其ORF5基因与美洲型代表毒株VR-2332的同源性为90.5％,与中国的经典毒株CH-1a的同源性为92.5％,与中国高致病性PRRSV毒株的同源性在98.0％以上；进化树分析结果显示,NJGC株和高致病性PRRSV在同一进化分支,推测其属于高致病性PRRSV,且与2006年分离的SY0608有更近的亲缘关系,体现了PRRSV具有一定的地域性.同时,该基因编码蛋白的抗原表位和抗原性也发生了变化.依据序列推断PRRSV NJG,C株属于具有明显地域性的高致病性PRRSV.%To analyze the genetic variation of porcine reproductive and respiratory syndrome virus (PRRSV) in Jiangsu Province, the 0RF5 genes of PRRSV strain NJGC were amplified, cloned and sequenced by RT-PCR, and blasted with the representative isolates using DNAstar software. The results showed that PRRSV isolate NJGC belonged to the North American genotype. The 0RF5 gene of strain NJGC shared 90.5% sequence similarity with the North American prototype VR-2332, 92.5% similarity with CH-la, the first PRRSV isolate in mainland China in 1996, and over 98.0% similaritywith the highly pathogenic PRRSV. The phylogenetic tree indicated that the PRRSV NJGC possed a same branch with the highly pathogenic PRRSV, and shared a closer relationship with the SY0608. The typical geographic genetic relationship existed in the Jiangsu strain of PRRSV. Meanwhile, there are changes in the epitopes and the antigeni-city of ORF5 encoded protein.