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Abstract：
Infectious bronchitis virus (IBV) is caused by avian coronavirus and poses a global economic threat to the poultry industry. In 2023, a highly pathogenic IBV strain, IBV/CN/GD20230501, was isolated and identified from chickens vaccinated with IBV-M41 in Guangdong, China. This study comprehensively investigated the biological characteristics of the isolated IBV strain, including its genotype, whole genome sequence analysis of its S1 gene, pathogenicity, host immune response, and serum non-targeted metabolomics. Through the analysis of the S1 gene sequence, serum neutralization tests, and comparative genomics, it was proven that IBV/CN/GD20230501 belongs to the GI-I type of strain and is serotype II. One alanine residue in the S1 subunit of the isolated strain was mutated into serine, and some mutations were observed in the ORF1ab gene and the terminal region of the genome. Animal challenge experiments using the EID50 and TCID50 calculations showed that IBV/CN/GD20230501 possesses strong respiratory pathogenicity, with early and long-term shedding of viruses and rapid viral spread. Antibody detection indicated that chickens infected with IBV/CN/GD20230501 exhibited delayed expression of early innate immune genes, while those infected with M41 showed rapid gene induction and effective viral control. Metabolomics analysis demonstrated that this virus infection led to differential expression of 291 ions in chicken serum, mainly affecting the citric acid cycle (tricarboxylic acid cycle).IMPORTANCEThis study identified an infectious bronchitis virus (IBV) strain isolated from vaccinated chickens in an immunized population that had certain sequence differences compared to IBV-M41, resulting in significantly enhanced pathogenicity and host defense. This strain has the potential to replace M41 as a more suitable challenge model for drug research. The non-targeted metabolomics analysis highlighting the citric acid cycle provides a new avenue for studying this highly virulent strain.
摘要：
传染性支气管炎病毒（IBV）由禽冠状病毒引起，对家禽业构成全球经济威胁。2023年，高致病性IBV株，从广东接种IBV-M41的鸡中分离鉴定出IBV/CN/GD20230501,中国。本研究全面调查了分离的IBV菌株的生物学特性，包括它的基因型，全基因组序列分析其S1基因，致病性，宿主免疫反应，和血清非靶向代谢组学。通过对S1基因序列的分析,血清中和试验,和比较基因组学，已证明IBV/CN/GD20230501属于GI-I型菌株并且是血清型II。分离菌株的S1亚基中的一个丙氨酸残基突变为丝氨酸，在ORF1ab基因和基因组末端区域观察到一些突变。使用EID50和TCID50计算的动物攻击实验表明，IBV/CN/GD20230501具有很强的呼吸道致病性，病毒的早期和长期脱落以及病毒的快速传播。抗体检测表明，感染IBV/CN/GD20230501的鸡表现出早期先天性免疫基因的延迟表达，而感染M41的患者表现出快速的基因诱导和有效的病毒控制。代谢组学分析表明,这种病毒感染导致鸡血清中291个离子的差异表达,主要影响柠檬酸循环(三羧酸循环)。重要意义本研究鉴定了从免疫群体中的接种鸡分离的传染性支气管炎病毒(IBV)株,其与IBV-M41相比具有某些序列差异,导致显著增强的致病性和宿主防御。该菌株有潜力取代M41作为更适合药物研究的挑战模型。强调柠檬酸循环的非靶向代谢组学分析为研究这种高毒力菌株提供了新的途径。
