MDV CVI988/Rispens弱毒株VP22基因克隆和序列分析

血清I型马立克氏病病毒(MDV-1)的UL49h基因编码病毒被膜蛋白VP22在病毒的复制和传播过程中具有非常重要的作用.根据已发表的MDV-1 GA株的序列,从CVI988/Rispens弱毒株感染的鸭胚成纤维细胞中扩增VP22基因片段,结果获得大小为732 bp的PCR产物.将PCR产物克隆T载体并测序分析,结果发现,与经典强毒GA株相比,弱毒株CVI988的VP22存在3个定点突变和一个缺失性突变.缺失的位点亲水性强,并位于VP22主要的抗原决定簇区.结果证明强毒株与弱毒株的VP22存在明显差异,为利用CVI988 VP22的蛋白传导域传导目的蛋白奠定了理论基础.

SEQUENCE ANALYSIS OF TEGUMENT PROTEIN VP22 ENCODED BY ATTENUATED STRAIN OF MAREK'S DISEASE VIRUS

A pair of primers specific to VP22 gene was designed on the basis of the reported UL49h sequence of GA strain of Marek's disease virus (MDV). UL49h fragments were amplified by PCR from the genome DNAs, which were extracted from Duck embryo fibroblast (DEF) cells infected with different reference strains: GA and CVI988/Rispens. The fagments were then cloned into T-tailed vector pGEM-T easy. Sequence analysis demonstrated that the size of attenuated strain CVI988/Rispens VP22 was 732 bp. Compared with oncogenic strain GA, there were four mutations: a deletion of one motif, and three site mutations. These results show that there is a significant difference in VP22 gene between virulent and avirulent strains of MDVs. Whether these mutations have effects on the protein transduction domain and functions of VP22 will be investigated in the future.