传染性法氏囊病病毒的分离及其VP2高变区序列的比较

目的]从病鸡中分离传染性法氏囊病病毒(IBDV),并对其VP2基因高变区序列进行比较。方法]采用鸡胚绒毛尿囊膜(CAM)接种SPF鸡胚的方法分离到2株IBDV。对分离株(vVP2)进行扩增和序列测定,分析分离株的关键氨基酸位点特征,并与参考毒株相应序列进行同源性比较。结果]2株分离株特征性位点的氨基酸为222A、249Q、254G、256I、279D、284A、294I和299S,属于wIB-DV的特征,与wIBDV参考株具有较高的同源性,其核苷酸和氨基酸同源性分别为96.0%～97.0%和98.7%～99.4%。从遗传进化树来看,2个分离株与参考的vvIBDV也在一个分支。此外,2个分离株表现出与该鸡场常用的疫苗株MB有较高的同源性,其核苷酸和氨基酸同源性分别为96.8%和98.1%,并在遗传进化树中同属于一个大分支,但其特征性位点的氨基酸明显不同。在其他氨基酸位点上,2个分离株均发生了D212N的特有变化。结论]该鸡群感染的IBDV具有vvIBDV的分子特征,并发生了与疫苗株和参考株不同的分子变化。

Isolation of Infectious Bursal Disease Viruses and Sequence Analysis of Their Hypervariable Region of VP2 Gene

Objective] The research aimed to isolate infectious bursal disease virus(IBDV)from diseased chicken and compare the sequences of its hypervariable region of VP2 gene.Method] Two strains(WM12061and WM12062) of IBDV were isolated by inoculating SPF chicken embryo with chorio-allantoic membrane(CAM).vVP2 of the two isolates were amplified and sequenced,the characteristics of key amino acid loci were analyzed and the sequence homology of reference strain was compared.Result] The amino acids of the characteristic locus of the two isolates were 222A,249Q,254G,256I,279D,284A,294I and 299S,which belonged to the features of wIBDV.The two isolates and wIBDV reference strain had higher homology with the nucleotide and amino acid homology of 96.0%-97.0% and 98.7%-99.4% respectively.In the phylogenetic tree,the two isolates and vvIBDV reference strain belonged to the same branch.And the two isolates and common vaccine strain MB in this chicken farm had higher homology with the nucleotide and amino acid homology of 96.8% and 98.1% respectively.They were classified to the same big branch,but the characteristic amino acids in vVP2 were significantly different.Furthermore,the 2 isolates showed unique amino acid mutation in D212N.Conclusion] The infectious IBDV in this flock had the molecular characteristics of vvIBDV and showed different mutation from MB strain and reference strains.