安徽地区IBDV超强毒株的分离鉴定和VP2基因序列分析

经鸡胚绒毛尿囊膜(CAM)接种、易感鸡接种试验、电镜观察,从安徽地区疑似病鸡的法氏囊组织分离到3株传染性法氏囊病毒。分离株人工感染4周龄鸡,致死率分别为92%、83%、67%。接种9～10SPF鸡胚测得的鸡胚半数致死量(ELD50)分别为10-6.8/0.2mL、10-5.4/0.2mL、10-4.6/0.2mL。应用Nested-PCR分别对3株分离株VP2基因高变区进行克隆测序和序列分析,结果表明:3个分离株与国内外参考超强毒株的核苷酸同源性为97.2%～99.5%,氨基酸同源性为99.3%～100%,VP2高变区核苷酸和推导的氨基酸符合传染性法氏囊病病毒超强毒株特征。

Isolation and identification of very virulent IBDVs from Anhui and sequencing of VP2 variable regions

Three strains of infectious bursal disease virus(IBDV)were isolated and identified from infected chickens in Anhui by embryo inoculation,AGP test and electronic microscope observation.4-week-old chickens,which were unvaccinated with IBDV,were inoculated with the three isolates and experienced severe clinical disease with the mortalities of 92%,83% and 67%.The ELD_ 50 of 3 isolates were 10-6.8/0.2 mL,10-5.4/0.2 mL and 10-4.6/0.2 mL,respectively.The VP2 hypervariable regions(vVP2)were amplified by RT-PCR/Nested PCR.Sequence analysis of the amplified products showed that the isolates shared the nucleic acid homology of 97.2%～99.5% and the amino acid homology of 99.3%～100% with referential very virulent infectious bursal disease virus(vvIBDV).The results demonstrated that these 3 isolates were classified to be vvIBDV since they possessed the characteristics of vvIBDV but attenuated or variant IBDV.