RESUMEN
Five field strains of infectious bronchitis virus (IBV) were isolated from suspected flocks from different time and different regions of Shanxi province,respectively,and characterized by a series of systematic identification assays,such as morphological observation by electron-microscope,interfering with the propagation of NDV,virus pathological role to chicken embryo,virus pathological role to SPF chickens,hemagglutination activity,physiscochemical,and reverse transcription polymerase chain reaction(RT-PCR).The results showed:The typical coronavirus which the spherical virions 60-120 nm in diameter and surface covered with spike like corona were observed under electron-microscope)The propagation of NDV strain was seriously interfered by the 5 isolates respectively;The embryonated chicken egg passages of the 5 isolates could dwarf with chicken embryos;The five isolates had no hemagglutination activity,but after treatment with 1% trypsin,it can agglutinate chicken red blood cell.The strains are sensitive to chloroform and ethyl ether.The SPF chickens which inoculated with the 5 isolates showed clinical sign and result in respiratory and kidney diseases,flower-steak,and swollen with severe urate deposition.The specific fragments of N gene of the 5 isolates were amplified by RT-PCR,respectiveiy.On the basis of all above mentioned results,the 5 isolates were classified as IBV.The study got a good preparedness for further study on molecular epidemioogy of the 5 IBV isolates.