2012～2013年鸡传染性支气管炎病毒广西分离株S1基因序列分析与血清型鉴定

Sequencing and Serologic Identification of S1 Genes of Infectious Bronchitis Viruses Isolated during 2012-2013 in Guangxi Province,China

为继续跟踪了解近年来广西鸡传染性支气管炎病毒（infectious bronchitis virus,IBV）的流行状况及抗原变异情况,本研究对2012~2013年的15个广西IBV分离株S1基因进行了相似性比较、进化树和重组分析,同时鉴定了分离株的血清型。结果表明,15个IBV毒株之间的S1基因氨基酸序列相似性为54.3%~99.6%,与参考株的相似性为43.3%~99.3%;除GX-YL130025外,其余14个毒株与疫苗株H120的相似性均较低（65.1%~81.4%）;进化树分析表明,15个IBV分离株分属8个基因型,其中New-type II为优势基因型;重组分析表明,分离株GX-NN130048的S1基因来源于4/91疫苗株和LX4型野毒株的重组;血清分型结果表明,15个IBV分离株分属7个血清型,与生产上广泛使用的疫苗株H120血清型一致的仅有1株,重组毒株GX-NN130048的血清型不同于其亲代血清型。本研究表明,近年广西地区IBV不管是在基因型还是血清型上都发生了明显的变异,同时存在多个基因型和血清型的流行;基因重组可导致新血清型的出现,这可能是导致免疫失败的主要原因。本研究为全面阐述IBV变异规律和分子机制以及为新疫苗的研发提供依据。

We wished to ascertain the prevalence as well as the genetic and antigenic variation of infectious bronchitis viruses（IBVs）circulating in the Guangxi Province of China in recent years.The S1 gene of 15 IBV field isolates during 2012-2013 underwent analyses in terms of the similarity of amino-acid sequences,creation of phylogenetic trees,recombination,and serologic identification.Similarities in amino-acid sequences among the 15 isolates of the S1 gene were 54.3%~99.6%,and 43.3%~99.3% among 15 isolates and reference strains.Compared with the vaccine strain H120,except for GX-YL130025,the other14 isolates showed a lower similarity of amino-acid sequences of the S1gene（65.1-81.4%）.Phylogenetic analyses of the S1 gene suggested that 15 IBV isolates were classified into eight genotypes,with the predominant genotype being new-type II.Recombination analyses demonstrated that the S1 gene of the GXNN130048 isolate originated from recombination events between vaccine strain 4/91 and a LX4-like isolate.Serotyping results suggested that seven serotypes prevailed during 2012-2013 in Guangxi Province,and that only one isolate was consistent with the vaccine strain H120 in serotype（which has been used widely in recent years）.The serotype of recombinant isolate GX-NN130048 was different from those of its parent strains.These results suggested that not only the genotype,but also the serotype of IBV field isolates in Guangxi Province had distinct variations,and that increasing numbers of genotypes and serotypes are in circulation.We showed that recombination events can lead to the emergence of new serotypes.Our study provides new evidence for understanding of the molecular mechanisms of IBV variations,and the development of new vaccines against IBVs.