Key Laboratory of Bio-Resources and Eco-Environment, Ministry of Education, College of Life Science, Sichuan University, Chengdu, 610064, China; Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, Chengdu, 610064, China.
College of Life Science and Engineering, Southwest University of Science and Technology, Mianyang, 621010, China.
Microb Pathog. 2022 Mar;164:105437. doi: 10.1016/j.micpath.2022.105437. Epub 2022 Feb 2.
Infectious bronchitis virus (IBV) causes avian infectious bronchitis (IB) and there are multiple serotypes worldwide originating from deletions, insertions, point mutations, and RNA recombination. In this study, a recombinant IBV, named CK/CH/MY/2020, was isolated from southwest China. Sequencing and phylogenetic analysis revealed that CK/CH/MY/2020 consists of 27,614 nucleotides and belongs to the GI-28 genotype. Moreover, the strain is a recombination product originating from three live attenuated vaccine strains (H120, 4/91, and LDT3-A). The recombination is complicated involving at least nine recombination sites; the first 3/5 portion is mainly composed of H120 and 4/91, and the second 2/5 contains LDT3-A. Pathogenicity analysis showed that CK/CH/MY/2020 could cause respiratory and kidney diseases in chickens resulting in moderate mortality. Therefore, the recombinant strain is more virulent than the attenuated vaccine strains. This study shows that even in the absence of wild strains, the recombination and revirulence of multiple attenuated vaccines could occur simultaneously, which also highlights the continuous evolution in IBV.
传染性支气管炎病毒（IBV）可引起禽传染性支气管炎（IB），全世界有多种血清型，其起源于缺失、插入、点突变和 RNA 重组。本研究从中国西南部分离到一株重组 IBV，命名为 CK/CH/MY/2020。测序和系统发育分析表明，CK/CH/MY/2020 由 27614 个核苷酸组成，属于 GI-28 基因型。此外，该株是由三种活疫苗株（H120、4/91 和 LDT3-A）衍生的重组产物。重组涉及至少 9 个重组位点，前 3/5 部分主要由 H120 和 4/91 组成，后 2/5 部分包含 LDT3-A。致病性分析表明，CK/CH/MY/2020 可引起鸡的呼吸道和肾脏疾病，导致中等死亡率。因此，重组株比减毒疫苗株更具毒力。本研究表明，即使没有野毒株，多种减毒疫苗的重组和返强也可能同时发生，这也突显了 IBV 的持续进化。
