College of Animal Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, China.
Viruses. 2013 Dec 4;5(12):3007-20. doi: 10.3390/v5123007.
To gain comprehensive genetic information of circulating avian coronavirus infectious bronchitis virus (IBV) isolates in China, analysis of the phylogenetic tree, entropy of the amino acid sequences, and the positive selection as well as computational recombinations of S1, M and N genes of 23 IBV isolates was conducted in the present study. The phylogenetic trees based on the S1, M and N genes exhibited considerably different topology and the CK/CH/LSC/99I-type isolates were the predominant IBVs based on the phylogenetic analysis of S1 gene. Results of entropy of amino acid sequences revealed that the S1 gene had the largest variation; the M gene had less variation than the N gene. Positive selections were detected in not only S1 but also M and N gene proteins. In addition, five S1 gene recombinants between vaccine strain 4/91 and CK/CH/LSC/99I-type field isolate were confirmed. In conclusion, multiple IBV genotypes co-circulated; genetic diversity and positive selections existed in S1, M and N genes; 4/91 vaccine recombinants emerged in China. Our results show that field IBVs in China are continuing to evolve and vaccine strains may have an important role in the appearance of new IBV strains via recombination. In addition, the present study indicates that IBV evolution is driven by both generations of genetic diversity and selection.
为了全面了解中国流行的禽冠状病毒传染性支气管炎病毒（IBV）分离株的遗传信息，本研究对 23 株 IBV 分离株的 S1、M 和 N 基因的系统进化树分析、氨基酸序列的熵、阳性选择以及计算重组进行了分析。基于 S1、M 和 N 基因构建的系统进化树显示出明显不同的拓扑结构，基于 S1 基因的系统进化分析，CK/CH/LSC/99I 型分离株是主要的 IBV。氨基酸序列熵的结果表明，S1 基因变异最大，M 基因的变异小于 N 基因。S1 基因和 M、N 基因蛋白均检测到阳性选择。此外，还确认了 4/91 疫苗株与 CK/CH/LSC/99I 型野毒株之间的 5 个 S1 基因重组。综上所述，多种 IBV 基因型共同流行，S1、M 和 N 基因存在遗传多样性和阳性选择，4/91 疫苗重组株在中国出现。本研究表明，中国的野毒株 IBV 仍在不断进化，疫苗株可能通过重组在新的 IBV 株的出现中发挥重要作用。此外，本研究表明，IBV 的进化是由遗传多样性和选择的共同作用驱动的。
