鸡传染性支气管炎病毒ck/CH/LHB/121042毒株的分离鉴定及分子特征研究

鸡传染性支气管炎病毒(infectious bronchitis virus,IBV),严重威胁养禽业健康发展。近年来,我国不断出现新型IBV毒株及变异株,给传染性支气管炎(infectious bronchitis,IB)防控造成困难。监测研究报告显示,IBV感染与多种类型毒株有关,主要以LX4型为主。我国部分地区近期出现LX4型与TW型重组毒株,但鲜有TWⅡ毒株报道,其分子特征和抗原特性目前尚不清楚。通过分离河北省某鸡场疑似IB病鸡肾脏,获得传染性支气管炎病毒ck/CH/LHB/121042,基因组全长27 675 bp,共10个开放阅读框,基因组特征为5'UTR-1a-1b-S-3a-3b-3c-M-5a-5b-N-3'UTR,Spike protein裂解酶识别位点为"Arg-Arg-Phe-Arg-Arg"。病毒基因型鉴定为TWⅡ型,基因组遗传进化分析表明,该毒株与2010年河北分离株ck/CH/LHB/100801亲缘关系最近,推测具有相同进化来源。研究结果对于阐明病毒起源、预测未来产生新型毒株和重组毒株等具有重要意义。

Isolation,identification and molecular characteristics of avian infectious bronchitis virus ck/CH/LHB/121042 isolate

Infectious bronchitis virus (IBV),caused considerable damage to poultry industry,exists in a wide range of the world.In recent years,new genotypes of IBV and associated variants appeared frequently in different parts of China,resulting in a major obstacle for the prevention and control of this pathogen.Surveillance studies have reported that widespreadly IBV infection in China is related to multiple types.Of these,LX4 (QX-like) is the predominant type circulating in chicken flock.However,in a recent study,recombinant IBV originated from QX-type and TW-type strains was reported in some parts of China.Up to now,a few reports on TW Ⅱ strains is officially demonstrated in China.As the result,the molecular and antigenic characteristics of lWⅡstrains were not clear.In this study,an avian infectious bronchitis virus,designated as cklCH/LHB/121042,was isolated and identified from kidney of chickens,which was suspected to be infected with IBV in Hebei Province,China.The result showed that ck/CH/LHB/121042 strain was 27 675 bp,with 10 ORFs,characterized by the 5'-cas-Replicase-S-3a-3b-3c-M-5a-5b-N-poly(A)-3'gene order,and the typical avian coronavirus cleavage site of spike protein contained five consecutive basic amino acids,namely,Arg-Arg-Phe-Arg-Arg.Based upon data arising from S1 sequence and phylogenetic analysis,the isolate was TW Ⅱ genotype and closely related to ck/CH/LHB/100801 strain.Based on this finding,it was speculated that this IBV might derive from ck/CH/LHB/100801 strain.Retrospective studies,involving molecular characterization,are necessary to clarify the origin of the viruses and are significant for the prediction of new variants and recombinants.