鸡传染性支气管炎病毒变异株DB4的分离鉴定

从东北养鸡场分离到DB4鸡传染性支气管炎病毒毒株，对其进行了动物回归、生物学特性、电镜观察与S1基因的序列分析等研究。结果表明：DB4能够凝集鸡的红细胞，形态为典型的冠状病毒粒子，鸡胚半数感染量为10^-6.7 EID50，动物回归感染死亡鸡肾脏病变明显，表现肾脏肿大、花斑肾，DB4毒株S1基因由1620个核苷酸组成，推导的多肽由540个氨基酸残基组成，氨基酸切割识别位点序列为HRRRR，序列分析发现：DB4与国内疫苗株YM_W93和标准株M41氨基酸同源性分别为77．2％和77．3％，确定该分离毒株为致肾脏病变的变异型IBV。

Isolation and Identification of an Avian Infectious Bronchitis Virus

A field DB4 strain of infectious bronchitis virus was isolated from chicken kidney of the affected chicken.Biological characteristics of the virus was studied by virus pathogenicity to chicken embryo,morphological observation by electron-microscope,hemagglutination activity,virus pathogenicity to chickens and S1 gene of the DB4 isolate was analyzed with the published genes of IBV strains.The results showed that the gross lesions in kidney of dead chicken caused by the isolate were distinct and the S1 gene of DB4 was composed of 1620 bp encoding a polypeptide of 540 amino acids.The cleavage site sequence of S protein of DB4 contained five consecutive basic amino acids,namely,His-Arg-Arg-Arg-Arg(HRRRR).Sequence data demonstrated that the S1 amino acid sequences of DB4 isolate shared 76.2% and 76.3% similarity with the published S1 sequences of YM_W93 M41.The DB4 virus was nephropathogenic avian infectious bronchitis virus.