The Pirbright Institutegrid.63622.33, Surrey, United Kingdom.
J Virol. 2022 Sep 14;96(17):e0110022. doi: 10.1128/jvi.01100-22. Epub 2022 Aug 16.
Avian coronavirus infectious bronchitis virus (IBV) is the etiological agent of infectious bronchitis, an acute highly contagious economically relevant respiratory disease of poultry. Vaccination is used to control IBV infections, with live-attenuated vaccines generated via serial passage of a virulent field isolate through embryonated hens' eggs. A fine balance must be achieved between attenuation and the retention of immunogenicity. The exact molecular mechanism of attenuation is unknown, and vaccines produced in this manner present a risk of reversion to virulence as few consensus level changes are acquired. Our previous research resulted in the generation of a recombinant IBV (rIBV) known as M41-R, based on a pathogenic strain M41-CK. M41-R was attenuated by two amino acid changes, Nsp10-Pro85Leu and Nsp14-Val393Leu; however, the mechanism of attenuation was not determined. Pro85 and Val393 were found to be conserved among not only IBV strains but members of the wider coronavirus family. This study demonstrates that the same changes are associated with a temperature-sensitive () replication phenotype at 41°C , suggesting that the two phenotypes may be linked. Vaccination of specific-pathogen-free chickens with M41-R induced 100% protection against clinical disease, tracheal ciliary damage, and challenge virus replication following homologous challenge with virulent M41-CK. Temperature sensitivity has been used to rationally attenuate other viral pathogens, including influenza, and the identification of amino acid changes that impart both a and an attenuated phenotype may therefore offer an avenue for future coronavirus vaccine development. Infectious bronchitis virus is a pathogen of economic and welfare concern for the global poultry industry. Live-attenuated vaccines against are generated by serial passage of a virulent isolate in embryonated eggs until attenuation is achieved. The exact mechanisms of attenuation are unknown, and vaccines produced have a risk of reversion to virulence. Reverse genetics provides a method to generate vaccines that are rationally attenuated and are more stable with respect to back selection due to their clonal origin. Genetic populations resulting from molecular clones are more homogeneous and lack the presence of parental pathogenic viruses, which generation by multiple passage does not. In this study, we identified two amino acids that impart a temperature-sensitive replication phenotype. Immunogenicity is retained and vaccination results in 100% protection against homologous challenge. Temperature sensitivity, used for the development of vaccines against other viruses, presents a method for the development of coronavirus vaccines.
禽冠状病毒传染性支气管炎病毒（IBV）是传染性支气管炎的病原体，传染性支气管炎是一种急性、高度传染性、具有经济重要性的家禽呼吸道疾病。疫苗接种用于控制 IBV 感染，通过在鸡胚中连续传代强毒分离株来生成活疫苗。必须在衰减和保持免疫原性之间取得良好平衡。衰减的确切分子机制尚不清楚，并且以这种方式生产的疫苗存在返祖为毒力的风险，因为很少获得共识水平的变化。我们之前的研究产生了一种称为 M41-R 的重组 IBV（rIBV），它基于一种致病性菌株 M41-CK。M41-R 通过两个氨基酸变化 Nsp10-Pro85Leu 和 Nsp14-Val393Leu 减弱，但是衰减机制尚未确定。Pro85 和 Val393 在不仅在 IBV 株中而且在更广泛的冠状病毒家族成员中都被发现是保守的。这项研究表明，相同的变化与 41°C 时的温度敏感（ts）复制表型相关，这表明两种表型可能相关。用 M41-R 对无特定病原体鸡进行接种，可在同源性强毒 M41-CK 攻毒后，100%抵抗临床疾病、气管纤毛损伤和攻毒病毒复制。温度敏感性已被用于合理减弱其他病毒病原体，包括流感，因此鉴定赋予 ts 和减弱表型的氨基酸变化可能为未来冠状病毒疫苗的开发提供了途径。传染性支气管炎病毒是全球家禽业具有经济和福利意义的病原体。针对的活疫苗通过在鸡胚中连续传代强毒分离株来生成，直到达到衰减。确切的衰减机制尚不清楚，并且生产的疫苗有返祖为毒力的风险。反向遗传学提供了一种生成合理减弱且由于其克隆起源而对反向选择更稳定的疫苗的方法。由于分子克隆产生的遗传群体更均匀，并且缺乏通过多次传代产生的亲代致病性病毒的存在。在这项研究中，我们鉴定了赋予温度敏感复制表型的两个氨基酸。免疫原性得以保留，接种疫苗可 100%抵抗同源性攻毒。用于开发其他病毒疫苗的温度敏感性为开发冠状病毒疫苗提供了一种方法。
