传染性法氏囊病病毒YL051、YL052的分离及其VP2基因高变区序列的比较分析

Isolation of infectious bursal disease viruses YL051,YL052 and sequence analysis of their hypervariable region of VP2 genes

应用鸡胚绒毛尿囊膜接种的方法，从一个疑患传染性法氏囊病的鸡群中分离到2株传染性法氏囊病病毒（IBDV）（分别命名为YL051和YL052）；利用反转录-聚合酶链式反应技术扩增分离株VP2基因的高变区序列，并采用限制性内切酶分析技术和核苷酸序列测定技术，对分离株进行致病型鉴定及其基因差异的分析。结果表明：分离株YL051属IBDV的超强毒株（vvIBDV），而YL052株既具有强毒株的特征即七肽区（SWSASGS）和279D，但同时也具有284T的弱毒株特征，可能属于介于强毒株与弱毒株之间的一个中间型。与国内外参考毒株的序列比较分析发现：YL051与其他vvIBDV的核苷酸同源性达94％～97％；YL052则与经典毒株STC、疫苗株B87的核苷酸同源性均为94．3％。

Two isolates of infectious bursal disease virus （IBDV）, named YL051 and YL052 respectively, were isolated from the chicken flock experienced infectious bursal disease by chorioallantoic membrane. The hypervariable region of VP2 gene of 2 isolates was amplified by Reverse Transcription-Polymerase Chain Reaction （RT-PCR）, and analyzed by restriction enzyme analysis and sequencing to identify pathotype and gene divergence of the isolates. The result indicated that YL051 belonged to very virulent IBDV （vvIBDV）, YL052 maybe classified as an intermediate type since it not only has the features of virulent virus ： the serine-rich heptapeptide sequence ＂SWSASGS＂ and residue 279D, but also has the features of attenuated virus： 284T. The sequences compared of 2 isolates with other reference strains indicated that there is 94%-97% homology between isolates YL051 and other vvIBDV, and there is 94.3%homology between isolates YL052 and the classical IEDV STC and attenuated vaccine strain B87.