鸡传染性法氏囊病超强毒株的分子鉴定

Molecular Identification of Very Virulent Infectious Bursal Disease Virus

通过RT-PCR方法从山西省不同地区养鸡场病、死鸡法氏囊组织中扩增得到IBDV SX/12 VP2基因全长,将其克隆至pMD18-T载体。测序分析结果表明,IBDV SX/12 VP2全长为1 356 bp,推导其编码452个氨基酸;核苷酸与氨基酸同源性分析显示,二者均与超强参考毒株同源性较高,分别为99.2%和99.6%;遗传进化树分析结果表明,IB-DV SX/12与超强参考毒株位于同一进化分支,IBDV SX/12高变区关键氨基酸具有以下特征:222S,249Q,254G,256I,279D,284A,294I,299S以及SWSASGS七肽区不变,超强参考毒株高变区关键氨基酸为:222A,249Q,254G,256I,279D,284A,294I,299S,除222S外,其他关键位点氨基酸均符合超强毒株特征,因此,从分子水平推断IBDV SX/12属于超强毒株。

The infectious bursal disease virus VP2 gene was amplified from bursa tissues of infected chickens in different areas of Shanxi province by RT-PCR,and then cloned to pMD18-T vector for sequence analysis.The results revealed that the SX/12 VP2 gene contained 1 356 nucleotides and encoded 452 amino acid.Compared with those other stains from GenBank,the SX/12 VP2 shared 99.2% homology with other very virulent infectious bursal disease virus（vvIBDV） strains at nucleotide level and 99.6% homology at amino acid level.The phylogenetic analysis showed that SX/12 was in the same lineage with the vvIBDV reference strains.The key amino acid in hypervariable region except 222（S） represented the typical feature of those of vvIBDV strains at the positions of 249（Q）,254（G）,256（I）,279（D）,284（A）,294（I）,299（S） and SWSASGS at positions of 326-332.These results demonstrated that SX/12 was classified to be vvIBDV.