Liu Huixin, Wang Chenchen, He Yang, Wei Xiaofang, Cheng Junze, Yang Wenwen, Shi Kaichuang, Si Hongbin
College of Animal Science and Technology, Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, Guangxi grass station, Nanning, China.
Poultry Disease Diagnosis Division, Guangxi Center for Animal Disease Control and Prevention, Nanning, China.
Microbiol Spectr. 2024 Aug 6;12(8):e0399023. doi: 10.1128/spectrum.03990-23. Epub 2024 Jun 21.
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 EID and TCID 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.
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，在中国广东，从接种过IBV-M41疫苗的鸡中分离并鉴定出一株高致病性IBV毒株，即IBV/CN/GD20230501。本研究全面调查了该分离株的生物学特性，包括其基因型、S1基因全基因组序列分析、致病性、宿主免疫反应和血清非靶向代谢组学。通过S1基因序列分析、血清中和试验和比较基因组学，证明IBV/CN/GD20230501属于GI-I型毒株，血清型为II型。分离株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EID和TCID计算进行的动物攻毒实验表明，IBV/CN/GD20230501具有很强的呼吸道致病性，病毒早期和长期排毒，传播迅速。抗体检测表明，感染IBV/CN/GD20230501的鸡早期固有免疫基因表达延迟，而感染M41的鸡基因诱导迅速，病毒得到有效控制。代谢组学分析表明，这种病毒感染导致鸡血清中291种离子差异表达，主要影响柠檬酸循环（三羧酸循环）。
重要性
本研究鉴定出一株从免疫群体中接种过疫苗的鸡中分离出的传染性支气管炎病毒（IBV）毒株，与IBV-M41相比具有一定的序列差异，导致致病性显著增强和宿主防御反应变化。该毒株有可能取代M41，成为更适合药物研究的攻毒模型。突出柠檬酸循环的非靶向代谢组学分析为研究这种高毒株提供了新途径。
