中文摘要：

查明猪繁殖与呼吸综合征病毒（PRRSV）致病性大幅增高的机制,进而研制用于防治流行PRRSV变异株的高效疫苗无疑是兽医工作者的当务之急。在弱毒株APRRS的全长感染性克隆pAPRRS以及我室构建的高致病性HP PRRSV感染性克隆pJX143的基础上,构建了nsp2替换的强弱毒PRRSV嵌合感染性克隆。将构建的嵌合克隆转染MA104,4d后观察到典型的CPE。通过RT-PCR和免疫荧光证明获得了一系列强弱毒株之间的嵌合病毒。这些嵌合病毒的构建成功和相应反向遗传操作平台的建立及应用,为研发预防HP PRRSV的高效嵌合疫苗奠定了基础。该类嵌合感染性cDNA克隆也为解析目前流行的HP PRRSV毒力因子和高致病力机制奠定了基础。

英文摘要：

Porcine reproductive and respiratory syndrome virus （PRRSV）, the causative agent of the ongoing ＂porcine high fever syndrome＂ in China, is capable of genetic and antigenic mutations at high frequency. How to design vaccine rationally to keep up with the ever-changing prevalent PRRSV variant is of great interest. In this study, based on an infectious cDNA clone of an atten- uated Type Ⅱ PRRSV strain pAPRRS and the highly pathogenic PRRSV cDNA clone pJX143, we replaced the coding sequence of pAPRRS nsp2 with those of the HP PRRSV to develop a series of chimeric clones. Upon transfection of chimeric clones into MA104 cells, typical PRRSV cyto- pathic effects were observed. This study provided a valuable tool to develop the chimeric PRRSV as vaccine candidate offering cross-protection to HP PRRSV strains. Furthermore, the infectious chimeric cDNA clone provides a powerful tool to molecular dissection of the mechanism of patho- genesis of the increasing-virulence of the on-going prevalent PRRSV in China.