Isolation and identification of an avian infectious bronchitis virus strain HN99

【Objective】 An experiment was carried out to isolate infectious bronchitis virus(IBV) from the diseased chickens in Henan Province.【Method】 Biological characteristics of the virus were studied by virus pathogenicity to chicken embryo,hemagglutination(HA) activity and interference effect on replication of NDV,pathogenicity to SPF chickens,physiochemical characteristics of the virus were also studied and morphological observed by electron-microscope.S1 and N genes were amplified by reverse transcription-polymerase chain reaction(RT-PCR).【Result】 The second passage virus produced gross lesions to chicken embryos.The virus could hemagglutinate chicken red blood cells about 29 and 27 after treatment with enzyme or phosphoesterase.Replication of NDV was affected by inoculating in the same chicken embryo after inoculation with the isolated virus.The morbidity and mortality of the four passage virus to 7-day-old chickens were 90% and 40%.Moreover,the gross lesions in kidney caused by the virus were distinct.In addition,physiochemical properties of the virus shared the typical characteristics of most strains of IBV.The virus showed typical shape shared by members of Coronaviridae under electron-microscope.S1 and N genes were amplified by RT-PCR and sequenced by automatic sequencing system.S1 gene consisted of 1 739 bp,N gene was 1 230 bp.Evolution analysis indicated that the isolated virus was distantly related to the other strains of IBV.【Conclusion】 All the results showed that the virus was a new IBV variant in China,and it was tentatively named HN99.