鸭新城疫病毒山东分离株的生物学特性与F基因遗传进化分析

Biological and genetically analysis of duck Newcasltle disease virus in Shandong province

从山东规模化鸭场采集棉拭子样品并接种SPF鸡胚分离鉴定NDV,通过测定鸡胚平均致死时间(MDT)和1日龄雏鸡脑内接种致死指数(ICPI)来确定分离株的毒力,采用RT-PCR方法对分离株F基因进行测序并进行遗传进化分析。结果显示,从正常鸭群棉拭子中分离到4株NDV,F蛋白裂解位点的氨基酸序列表明4个分离株中2株氨基酸序列为112 ERQERL117,1株为112 GKQGRL117,符合弱毒株序列特征;1个分离株为112 RRQKRL117,符合强毒株序列特征。系统进化分析表明,其中2株属于ClassⅠ分支、2株属于ClassⅡ分支,ClassⅡ分支中的2个分离株1个为基因Ⅶ型强毒株,1个属于基因Ⅰ型弱毒株,与Queensland V4等毒株的同源性较高。

In order to better understand the prevalence and virulence evolution of Newcastle disease virus in duck of Shandong province,swabs samples were collected from duck farm and NDVs were isolated in SPF embryonated eggs.The isolates were characterized biologically and genetically.Fusion protein(F)genes of the isolates were amplified by reverse transcription-polymerase chain reaction and F gene sequence were conducted phylogenetic analysis.Cleavage site analysis of the F-protein precursor for these viruses showed that two isolates was112 ERQERL117,one was112 GKQGRL117,together with ICPI and MDT index,three isolates were all in accordance with avirulent NDVs characteristics.Cleavage site of one isolate was 112 RRQKRL117,in accordance with virulent NDVs.Phylogenetic analysis indicated that two isolates clustered into classⅠ clade and two clustered into ClassⅡ clade.In classⅡ clade,one isolate belonged to genotype Ⅶ virulent strain,one isolate belonged to genotypeⅠ avirulent strain and shared high homology with Queensland V4 strain.