摘要
用RT-PCR方法从2007年12月在安徽境内发生的两起传染性腔上囊病(IBD)免疫预防失败的病鸡腔上囊组织样品AH1与AH2中扩增出了传染性腔上囊病病毒(IBDV)VP2基因。序列分析表明,AH1与AH2病毒VP2基因长度均为1350 nt,编码450 aa,七肽基序均为S-W-S-A-S-G-S,在222、253、256、279、284、294和299位上的氨基酸残基分别是A、QI、、D、AI、和S,具有IBDV强毒的分子特征,AH1和AH2感染的20日龄雏鸡产生明显IBD病变,死亡率为25%(1/4)。同源性分析表明,26个血清Ⅰ型IBDV毒株VP2基因核苷酸和氨基酸序列的同源性分别为90.7%~99.6%和95.5%~100%,不同IBDV毒株VP2基因的七肽基序、特征性氨基酸残基以及高变区的亲水性有差异。在进化树上,26个血清Ⅰ型IBDV毒株可分为数组,其中的15个中国分离IBDV毒株不在同组,毒株之间的亲缘关系与分离地区或分离时间没有明显的联系。AH1和AH2与现行商品疫苗毒株B87的VP2基因核苷酸序列的差异率分别为5.3%和5.2%,这也进一步佐证了IBDV野毒VP2基因变异所引起的毒力变化和VP2抗原表位的漂移是导致当前IBD疫苗免疫预防失败的主要原因。
VP2 genes of infectious bursal disease virus(IBDV)were amplified by reverse transcriptionpolymerase chain reaction(RT-PCR)from bursae of Fabricius AH1 and AH2 samples collected from 2 chicken farms with immunoprophylaxis defeat in Anhui Province in December'2007.Sequence analysis showed that the VP2 gene of AH1 and AH2 had 1350 nucleotides and encoded 450 amino acids.Both strains had the same heptapeptide motif(S-W-S-A-S-G-S)and critical amino acid residues A222,Q253,I256,D279,A284,I294 and S299 in the variable region of VP2 gene,suggesting that AH1 or AH2 possessed the molecular characteristics of virulent IBDV.Symptoms and pathological changes of IBD could be caused in 20-day-old chickens infected experimentally with AH1 or AH2,and the mortality was 25%(1/4).Clustering analysis indicated that the homology of to 100%based on the nucleotide and a acid residues and hydrophilic regions e lent)IBDV.In the phylogenetic tree,215 isolates from China were not in the 26 serotypeⅠisolates were from 90.7%to 99.6%and from 95.5%mino acid sequences,respectively.Heptapeptide motif,critical amino xisted differences between the virulent and attenuated (or non-viru-6 IBDV serotype I isolates could be divided into several groups,but same group,indicating that the branching order of the isolates had not been defined by geographic origins and separation time.The differences in VP2 gene sequence between AH1 or AH2 and current commercial vaccine strain B87 were 5.3G and 5.2%,respectively,indicating that the virulence change and antigenic epitope shift caused by VP2 variation of IBDV field strain were the major factors causing the failure of immunological protection using IBD vaccine.
作者
王永山
欧阳伟
潘群兴
范红结
张海彬
王忠灿
唐雨德
谭维国
WANG Yong-shan;OUYANG wei;PAN Qun-xing;FAN Hong-jie;ZHANG Hai-bin;WANG Zhong-can;TANG Yu-de;TAN Wei-guo(Veterinary Biomedicine Research Laboratory,Institute of Veterinary Medicine,Jiangsu Academy of Agricultural Sciences,Nanjing 210014,China;College of Veterinary Medicine,Nanjing Agricultural University,Nanjing 210095,China;Center for Disease Control and Prevention of Nanjing Command,Nanjing 210002,China)
出处
《中国兽医科学》
CAS
CSCD
北大核心
2008年第12期1013-1019,共7页
Chinese Veterinary Science
基金
国家自然科学基金项目(30571371)
江苏省自然科学基金项目(BK2008065,BK2008352)
关键词
传染性腔上囊病病毒
序列分析
VP2基因
分子特征
infectious bursal disease virus
sequence analysis
VP2 gene
molecular characteristics
