高致病性PRRSV缺失变异株Nsp2基因的克隆与遗传变异分析

从湖南省内多个出现疑似猪“高热病”症状的猪场采集病料70份，采用RT-PCR方法进行分子流行病学调查．结果检出PRRSV阳性病料54份，阳性率高达77．14％（54／70）．对其中8份分别来自娄底、浏阳、永州、双峰、益阳、株洲、宁乡和溆浦的病料中的PRRSV基因组Nsp2高变区部分基因片段进行RT-PCR扩增、克隆和序列测定分析．与国内外美洲型PRRSV分离株比较，序列相似性为72．2％～100％，其中，与公布的高致病性PRRSV缺失变异毒株的同源性最高，序列相似性为98．2％-100％．序列分析表明，这些毒株均是天然存在缺失的变异毒株，其Nsp2均有2个部位出现了缺失，分别为编码1个氨基酸的3个核苷酸的缺失和编码29个氨基酸的连续87个核苷酸的缺失，与高致病性PRRSV缺失变异毒株序列的缺失情况完全一致，且与其具很高的同源性，从而确定了分离的毒株均为引起猪“高热病”的猪繁殖与呼吸综合征病毒变异株，这是国内外少见的PRRSV缺失变异及毒力显著增强的现象．

Cloning and genetic variation analysis of Nsp2 gene of highly virulent PRRSV mutant strains with deletions

A total of 70 samples from swine with likely porcinehigh feverdisease symptom,collected in various porcine farms in Hunan province were tested for PRRSV by RT-PCR amplification.PRRSV were detected in 77.14%(54/70) of the samples.Amplification,cloning and sequencing analysis were conducted towards part of Nsp2 genetic fragments in highly variable section of genome PRRSV of the 8 samples,from the following area:Loudi,Liuyang,Yongzhou,Shuangfeng,Yiyang,Zhuzhou,Ningxiang and shupu in Hunan province.Comparative ...