鸡新城疫病毒河北分离株F基因的分子特性分析

通过毒力测定、RT-PCR及F基因的序列测定与遗传进化分析,对2005-2008年从河北省部分地区的发病鸡群中分离到的10株新城疫病毒（NDV）进行了研究。各分离株经典毒力测定结果显示：MDT在37.6～54.4h之间,ICPI在1.71～2.0之间,IVPI值在2.16～2.8之间,均为新城疫病毒强毒株特征。F基因的序列测定表明,分离株之间的核苷酸序列具有77.4%～98.0%的同源性,与疫苗株Lasota的同源性为87.0%～98.9%,与国内标准强毒株F48E9同源性为89.7%～98.9%。推导其氨基酸序列分析表明,8个分离株的F蛋白的裂解位点氨基酸组成为112 R-R-Q-K-R-F117,具有NDV强毒株特征,与毒力测定结果相符,2个分离株的F蛋白的裂解位点氨基酸组成为112 G-R-Q-G-R-L117,与弱毒株特征相符。F基因分型和同源性比较显示：目前河北新城疫的流行以基因Ⅶ型为主（占70%）,同时兼有基因Ⅱ型（占20%）和基因Ⅸ型（占10%）。

Molecular characterization of fusion protein gene of Newcastle disease virus isolated from Hebei province

Ten Newcastle disease virus（NDV） strains were isolated from chickens in the field outbreaks in some regions of Hebei province during 2004-2008.Assessment of the virulence by MDT,ICPI and IVPI,RT-PCR and sequence analysis of fusion protein gene were used to compare the properties of NDV isolates.The results indicated that MDT,ICPI and IVPI of the isolates were 37.6-54.4 h,1.71-2.0 and 2.16-2.8,respectively,indicating that the all NDV isolates were highly virulent.The results of nucleotide sequencing and phylogentic analysis of fusion protein gene showed that the ten strains shared homology from 77.4% to 98.0% among themselves,from 87.0% to 98.9% and from 89.7% to 98.9% with NDV Lasota,F48E8,respectively.The putative amino acid sequences of fusion protein at the cleavage sites of eight isolates were 112 R-R-Q-K-R-F117,with the motif characteristics of the virulent NDV strain;two isolates were 112 G-R-Q-G-R-L117,with the motif characteristics of the Lentongenic NDV strain.Phylogenetic analysis showed that the NDV epidemic belonged to 3 genotypes（II,Ⅶand Ⅸ） and the genotype VII（70%）was the major pathogeny causing the epizootic of ND in Hebei.