新城疫病毒ZJ1株F蛋白裂解位点突变对其融合活性的影响

新城疫病毒ZJ1毒株是近年来在我国水禽中流行并能引起水禽严重发病和死亡的强毒株，其F蛋白裂解位点有多个碱性氨基酸分布。将该毒株F蛋白裂解位点的112、115和117位碱性氨基酸突变成弱毒株特征的非碱性氨基酸，构建了重组表达质粒pCI-FT。分别将突变前后的F蛋白与该毒株的HN蛋白在COS-1细胞共表达，表明突变前后的F蛋白均有融合活性；分别将突变前后的F蛋白与该毒株的HN蛋白在CEF细胞共表达，表明突变后F蛋白被裂解的活性大大降低。以上研究为下一步在全长cDNA克隆水平上对F蛋白裂解位点氨基酸序列进行相应突变，研究毒力相关因素以及构建毒力致弱疫苗株等奠定基础。

Effect of Fusion Protein Cleavage Site Mutations of NDV ZJ1 Strain on Its Fusion Activity

NDV strain ZJ1 strain , a highly virulent NDV strain, has been prevalent among the waterfowls in China mainland in the past years. Multi-busic amino acid sequence distribute in the protease cleavage site of F protein of this strain. Recombinant expressing plasmid pCI-FT, was generated by converting multi-basic amino acid sequence of 112, 115, 117 of the protease cleavage site of F0 protein, to the non-basic amino acid sequence characteristic of avirulent NDV strain. The result from co-expression of mutant or parental F protein with homologous HN protein in COS-1 ceiLs revealed that both mutant and parental F protein had fusion activity. The result from co-expression of mutant or parental F protein with homologous HN protein in CEF ceiLs showed that the cleavage activity of mutant F protein was significantly reduced. The study built a foundation for mutagenesis of amino acid sequence of the protease cleavage site of F0 protein at the full-length cDNA clone level, study on factors contributing to vindence and construction of candidate vaccine strain, and so on.