一株Class Ⅰ新城疫病毒中国分离株分子特性的研究

对从健康家鸭中分离到的一株Class I新城疫病毒分离株Duck/China/08-004/2008进行了遗传进化特性研究。利用RT-PCR扩增了该分离株F基因的主要功能区片段,并进行了克隆与序列分析。序列测定结果已经登录到GenBank,登录号为EU589149。该分离株F蛋白裂解位点的组成为112E-Q-Q-E-R-L117,具有典型新城疫弱毒株的分子特征。同源性分析表明其与国内普遍使用的弱毒疫苗株LaSota和V4核苷酸的同源性较低(分别为55.4%和57.7%)。通过构建F基因的遗传进化树,结果表明该分离株在分类地位上属于ClassI,与我国目前普遍使用的弱毒疫苗株LaSota(Class II中的基因II型)和V4(Class II中的基因I型)处在不同的进化分支。通过构建57株ClassI新城疫病毒的遗传进化树,表明本分离株与近年来香港活禽市场分离株较为类似,同属于基因3型。

Characterization of a Class I Newcastle disease virus strain isolated from waterfowl in China

A Class I Newcastle disease virus strain,Duck/China/08-004/2008,isolated from healthy duck in China was characterized genotypically.The main functional region of the F gene comprising 433 nucleotides was amplified by RT-PCR and sequenced.The isolate was predicted to be lentogenic based on the sequence of fusion protein cleavage site(112E-Q-Q-E-R-L117).Sequence comparison with the live vaccine strain used in China revealed that the F gene of the isolate had a lower nucleotide homology with LaSota(55.2%) and V4(54.0%).For genotyping,a phylogenetic tree based on nucleotides 47-435 of the F gene was constructed.Phylogenetic analysis of the fusion gene identified two clusters,namely Class I and Class II.Among Class II,nine genotypes were identified respec-tively.The isolate was shown to be distinct from NDV used in live vaccines in China,namely LaSota and V4(genotype II and I among the Class II NDV).Phylogenetic analysis based on the 57 Class I NDV isolates revealed that the isolate was similar to the isolates obtained from live bird markets in Honkong in recent years,and all of them belong to genotype 3 in Class I.