新城疫不同毒株交叉鸡胚中和指数及其与F和HN基因变异的相关性

Correlation of the neutralization index in chicken embryo with the homolo-gies of F and HN gene of different Newcastle-Disease isolates

摘要:

选取13株国内2001～2004年分离的新城疫流行病毒(Newcastle disease virus, NDV), 经蚀斑纯化, 克隆其融合蛋白(F)和血凝素-神经氨酸酶(HN)基因, 结合疫苗株La Sota、Clone30和国内标准强毒株F48E9等的基因序列, 进行遗传变异分析。利用纯化的病毒制备特异阳性血清, 进行鸡胚交叉中和试验, 确定不同NDV毒株之间的抗原相关性, 并与NDV不同毒株之间的HN和F基因核苷酸(氨基酸)同源性进行相关比较。结果表明: 病毒中和指数与HN基因的核苷酸(氨基酸)同源性显著相关(P<0.01, r=0.35), 与F基因呈弱相关(P<0.05, r=0.20), 而与F基因前374bp的核甘酸同源性不相关。这表明, NDV的分子变异已经对NDV的抗原性变异产生了影响, 研制新型的疫苗成为必然。

Abstract:

Thirteen prevailed Newcastle-disease viruses (NDV) isolated in China during 2001-2004 were purified by chick embryo fibroblast (CEF) plaque assay and characterized pathotypically and genotypically. The biological tests showed that these viruses were highly virulent. Sequence analysis based on the variable region (nucleotide 47-420) of the F gene indicated that of the 13 NDV isolates 2 belonged to genotypeⅡ, 2 to genotype Ⅸ and 9 to genotype Ⅶ. Isolates with genotype Ⅶ shared 94.6%~99.3% nucleotide (nt) homology with the F gene, whereas for genotype Ⅶ and La Sota was only 82.7%~84.1%. In addition, these NDV isolates all shared 95.2%~100% nt homology with the hemagglutinin-neuraminidase (HN) gene, whereas only 79.1%~84.3% compared these viruses with La Sota. The cross neutralization assays were done using positive serums in specific pathogen free (SPF) chicken embryos respectively. Correlation of the neutralization index in chicken embryo with the homologies of F and HN gene of different NDV isolates were analyzed by SPSS8.0 software. The result showed that the neutralization index was closely correlated with nt sequence (P<0.01, r=0.35) or deduced amino acid sequence (P<0.01, r=0.34) of the HN gene, whereas weekly correlated (P<0.05, r=0.20 or 0.19) with the F gene, and non-correlated with 374 nt segment. This implied that the genetic mutations of HN resulted in antigenic variations of these viruses and the search for new vaccines would be necessary.