广东地区8株鹅源基因Ⅻ型新城疫病毒F蛋白基因遗传进化分析

Genetic evolution analysis of the F protein genes of eight Newcastle disease viruses isolated from gooses in Guangdong province

为了解当前广东地区鹅群新城疫病毒(NDV)遗传进化情况,本研究从广东养殖病死鹅组织样品中分离鉴定获得8株NDV,对分离株的F蛋白基因进行核苷酸及氨基酸序列分析。8株分离病毒之间F蛋白基因同源性较高,为96.3%-99.9%,但与当前国内NDV优势流行株及疫苗株同源性均较低。遗传进化分析结果显示所有新分离株均属于Ⅻ型NDVⅫb亚型分支,而当前国内NDV的优势流行株及常用疫苗株均属于Ⅶd亚型分支。氨基酸序列分析结果显示,本研究分离株F蛋白裂解位点氨基酸序列均为112K/RRQKR/F117,符合强毒株分子特征;与基因Ⅶ型代表株NDV/ZJ1相比,新分离株F蛋白B细胞中和抗原表位均出现D170N变异;而与2010年~2011年报道的广东Ⅻb亚型分离株相比,新分离株F蛋白疏水区、七肽重复序列等区域均出现氨基酸的变异。综上所述,本研究分离鉴定的8株鹅源NDV的F基因均属于Ⅻb亚型,与Ⅶd亚型流行株及常用疫苗株F基因同源性较低,且其多个氨基酸关键位点存在变异。本研究在国内首次从病死鹅体内分离到基因Ⅻ型NDV,为进一步了解基因Ⅻ型NDV在广东地区水禽中的流行、病原进化以及疫苗株更新提供参考。

To understand current epidemic situation and genetic evolution of Newcastie disease virus(NDV) in dead gooses in Guangdong provience,eight NDV isolates were collected from the tissue samples of local domestic gooses.The F protein genes of the eight isolates were cloned and subjected to gene sequencing followed by phylogenetic analysis and amino acid sequence analysis.Genetic evolution analysis of F protein gene showed that all of these eight isolates located in the Ⅻb sub-lineage with significant homologies from 96.3% to 99.9% with each other but low similarities with strains of Ⅶd sub-lineage,including current prevailing strains and main vaccine strains.The amino acid sequence analysis revealed the same amino acid sequence of the cleavage site of F protein in all new isolates,112K//RRQKR/F117,which has been known as one of the molecular characteristics of virulent strains.Moreover,cpmparison of the amino acid sequoences of F proteins between a reference strain of Ⅶ genoype NDV/ZJ1 and the eight new isolates identified a common D170N mutation in neutralizing B-cell epitope.Comparing with the F proteins of Ⅻb subgenotype NDV strains previously reported in Guangdong from 2010 to 2011,mutations in multi regions,including the hydrophobic area and heptad repeat regions(HR1 and HR2),were observed in the F proteins of the eight new isolates.To sum up,present study identified eight goose origin Ⅻb sub genotype NDV strains,which contain multi mutations in F proteins and share low homology with currentⅦd subgeontype prevailing strains and main vaccine strains.The Ⅻ genotype NDV was isolated from diseased gooses for the first time in China,the present study provides basic data for further understanding on the epidemic and genetic evolution of Ⅻ genotype NDV strains in waterfowl in Guangdong and serves as reference data for future update of vaccine strains.