中文摘要：

为研究鸡传染性法氏囊病病毒超强毒株（vvIBDV）细胞嗜性改变的分子基础,本研究通过定点突变、重叠延伸PCR（SOE-PCR）等技术,以vvIBDV HLJ-0504株为骨架构建了两组感染性克隆,并借助已建立的反向遗传操作技术进行病毒拯救。IFA检测、电镜观察及RT-PCR鉴定均显示：Q253H/A284T双点突变的pCAGGHLJ0504A889/980HRT和pCAGGHLJ0504BHRT共转染DF1细胞成功拯救出重组病毒（rHLJ0504HT）,而未进行双点突变的pCAGGHLJ0504AHRT和pCAGGHLJ0504BHRT共转染组未获得重组病毒。上述结果表明,双点突变Q253H/A284T能使vvIBDV HLJ-0504适应非允许细胞CEF,但未进行Q253H/A284T双点突变的vvIBDV HLJ-0504不能感染非允许细胞CEF,因此,该研究表明VP2的Q253H/A284T两个氨基酸突变是vvIBDV细胞嗜性改变的分子基础。

英文摘要：

To study the molecular basis of cell tropism of very virulent infectious bursal disease virus（vvIBDV）,a infectious clone based on the backbone of vvIBDV HLJ-0504 were constructed by overlap extension PCR（SOE PCR） and site-direct mutation.Recombinant viruse was rescued by reverse-genetics approach using the T7 RNA polymerase II transcription system.Cell tropism and the replication kinetics of the rescued IBDV in CEF cells were evaluated by IFA,electron microscope and RT-PCR.The results showed that the recombination virus rHLJ0504HT with double mutations at Q253H and A284T was successfully rescued and replicated in the CEF cells which was otherwise non-permissive to the non-mutated viruses vvIBDV.Consequently,the synergetic mutation of Q253H and A284T of VP2 changed the cell tropism of vvIBDV.