基因自然重排鸡传染性法氏囊病病毒的分子特征

Molecular Characteristic of Natural Gene Reassortant Infectious Bursal Disease Virus

为了对某鸡群疑似传染性法氏囊病(IBD)的病例进行分子诊断、病毒分离和分子特征分析,本试验通过核酸检测调查该鸡群法氏囊组织和病毒分离物中传染性法氏囊病病毒(IBDV)的感染情况,将分离得到的毒株命名为GL1906,继而对该病毒基因组双节段的VP2高变区(vVP2)序列和VP1-b序列进行分析。结果显示,GL1906 vVP2基因的特征性氨基酸位点在222A、256I、284A、294I和299S上均符合超强毒株(vvIBDV)的特征,但279N符合致弱毒株的特征;VP1-b基因在242D、390L、393E与弱毒株一致,287A与vvIBDV一致,此外第777~782位核苷酸序列为GGTGCC,与弱毒株一致;GL1906 vVP2的核苷酸、氨基酸序列与vvIBDV的同源性最高,在系统进化树中与vvIBDV同为A3分支;GL1906 VP1-b的核苷酸、氨基酸序列与B节段属于独特来源的NN1172同源性最高,在系统进化树中同属于B3独特分支。结果表明,本试验分离株GL1906的基因组双节段vVP2和VP1-b具有不同的来源,是基因型为A3B3的基因自然重排毒株。

This study investigated an infectious bursal disease(IBD) suspected case in a chicken flock using molecular diagnostic test, virus isolation and molecular characteristic analysis. Specifically, nucleic acid test was used to detect infectious bursal disease virus(IBDV) in bursa tissue and virus culture resulted in the isolation of a strain named GL1906. Further analysis of the hypervariable region of VP2(vVP2) and VP1-b sequences in the GL1906 genome showed that the vVP2 gene contained the characteristic amino acid(aa) sites 222A, 256I, 284A, 294I and 299S in line with that of very virulent IBDV(vvIBDV), but its 279N was consistent with that of the attenuated strain;the VP1-b gene possessed the characteristic aa sites 242D, 390L and 393E in line with that of the attenuated strain, its 287A was identical to that of the vvIBDV, the nucleotide sequence at position 777-782 was GGTGCC, which was the same as that of the attenuated strain. The vVP2 gene of GL1906 showed the highest homolgy with that of the vvIBDV strains in nucleotide and amino acid level, respectively, and the phylogenetic tree analysis grouped GL1906 in the branch of A3 with vvIBDV based on vVP2. However, GL1906 shared the highest similarity in VP1-b with NN1172, a strain with B segement derived from a unique origin, and the phylogenetic tree grouped GL1906 in the branch of B3 with NN1172. Thus, the A-vVP2 and B-VP1-b of the isolate GL1906 appeared to have dirived from different sources and was a natural gene reassortant virus strain with the genotype A3B3.