白斑综合征病毒江苏分离株变异区和缺失区基因的序列比较

摘要

为了解白斑综合征病毒(White spot syndrome virus,wssv)在养殖克氏原螯虾(Procambarus clarkii)中的感染流行情况和分子流行病学特征,以及探讨不同病毒株间的遗传进化差异,2008年7月至2010年6月在江苏各主要克氏原螯虾养殖产区共采集了83份样品,应用环介导等温扩增技术(LAMP)检测42份样品为病毒感染阳性,阳性率达50.6％.在此基础上考虑地理和时间因素选取了兴化、盱眙等地的6份样品,PCR扩增、克隆了样品中所携带病毒的变异区和缺失区基因并对其进行了测序.分析结果显示,在变异区除兴化毒株为1 829 bp之外,其余各分离株间差异微小,均在1 440 bp左右；而在缺失区各毒株大小均为384 bp,且核苷酸序列完全一致.随后将各分离株序列与GenBank已公布的毒株做进一步的序列比较分析,结果表明在江苏境内流行的兴化毒株与其余毒株间存在明显差异,在遗传上相距较远,并且推测WSSV变异区和缺失区可能是各自独立进化变异的；同时,缺失变小的病毒基因组更易于适应宿主和环境的变化.%We evaluated the prevalence of white spot syndrome virus (WSSV) in cultured crayfish {Procambarus clarkii) in Jiangsu Province, China. We collected 83 crayfish during the period between July 2008 and June 2010. Of these, 42 were tested positive for WSSV using the loop-mediated isothermal amplification method (LAMP). Based on geographical and time considerations, we selected six positive samples for amplification of the variable and deletion regions of the WSSV genome. In addition, we used PCR amplification to clone and sequence these regions. We then conducted a pairwise and multiple alignment analysis to evaluate the degree of genetic divergence between different strains. The variable region was ~1 440 bp in length in most strains, except in isolate WSSV-XH (1 829 bp). The deletion region was 384 bp in length in six strains, and there was complete homol-ogy among the nucleotide sequences. We compared the isolate sequences to those in GenBank and found at least two distinct types of WSSV in Jiangsu Province. Given this, we hypothesize that the WSSV variable region and the deletion region may have evolved independently.