Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China.
J Virol. 2022 Jun 22;96(12):e0068622. doi: 10.1128/jvi.00686-22. Epub 2022 May 31.
Infectious bronchitis virus (IBV), a γ-coronavirus, causes the economically important poultry disease infectious bronchitis. Cellular stress response is an effective antiviral strategy that leads to stress granule (SG) formation. Previous studies suggested that SGs were involved in the antiviral activity of host cells to limit viral propagation. Here, we aimed to delineate the molecular mechanisms regulating the SG response to pathogenic IBV strain infection. We found that most chicken embryo kidney (CEK) cells formed no SGs during IBV infection and IBV replication inhibited arsenite-induced SG formation. This inhibition was not caused by changes in the integrity or abundance of SG proteins during infection. IBV nonstructural protein 15 (Nsp15) endoribonuclease activity suppressed SG formation. Regardless of whether Nsp15 was expressed alone, with recombinant viral infection with Newcastle disease virus as a vector, or with EndoU-deficient IBV, the Nsp15 endoribonuclease activity was the main factor inhibiting SG formation. Importantly, uridine-specific endoribonuclease (EndoU)-deficient IBV infection induced colocalization of IBV N protein/dsRNA and SG-associated protein TIA1 in infected cells. Additionally, overexpressing TIA1 in CEK cells suppressed IBV replication and may be a potential antiviral factor for impairing viral replication. These data provide a novel foundation for future investigations of the mechanisms by which coronavirus endoribonuclease activity affects viral replication. Endoribonuclease is conserved in coronaviruses and affects viral replication and pathogenicity. Infectious bronchitis virus (IBV), a γ-coronavirus, infects respiratory, renal, and reproductive systems, causing millions of dollars in lost revenue to the poultry industry worldwide annually. Mutating the viral endoribonuclease poly(U) resulted in SG formation, and TIA1 protein colocalized with the viral N protein and dsRNA, thus damaging IBV replication. These results suggest a new antiviral target design strategy for coronaviruses.
传染性支气管炎病毒（IBV）是一种γ冠状病毒，可引起具有重要经济意义的家禽病传染性支气管炎。细胞应激反应是一种有效的抗病毒策略，可导致应激颗粒（SG）的形成。先前的研究表明，SGs 参与宿主细胞的抗病毒活性，以限制病毒的繁殖。在这里，我们旨在描绘调节 SG 对致病性 IBV 株感染反应的分子机制。我们发现，在 IBV 感染和 IBV 复制过程中，大多数鸡胚肾（CEK）细胞均未形成 SG，而亚砷酸盐诱导的 SG 形成受到抑制。这种抑制不是由于感染过程中 SG 蛋白的完整性或丰度发生变化所致。IBV 非结构蛋白 15（Nsp15）内切核酸酶活性抑制 SG 的形成。无论 Nsp15 是否单独表达，或使用以新城疫病毒为载体的重组病毒感染，或使用缺乏内切酶 U 的 IBV，Nsp15 内切核酸酶活性都是抑制 SG 形成的主要因素。重要的是，缺乏尿嘧啶特异性内切核酸酶（EndoU）的 IBV 感染诱导 IBV N 蛋白/dsRNA 和与 SG 相关的蛋白 TIA1 在感染细胞中的共定位。此外，在 CEK 细胞中过表达 TIA1 可抑制 IBV 复制，可能是一种潜在的抗病毒因子，可损害病毒复制。这些数据为进一步研究冠状病毒内切核酸酶活性影响病毒复制的机制提供了新的基础。内切核酸酶在冠状病毒中保守，影响病毒的复制和致病性。传染性支气管炎病毒（IBV）是一种γ冠状病毒，可感染呼吸道、肾脏和生殖系统，导致全球每年家禽业损失数百万美元。突变病毒的内切核酸酶多聚（U）导致 SG 的形成，并且 TIA1 蛋白与病毒的 N 蛋白和 dsRNA 共定位，从而破坏 IBV 的复制。这些结果为冠状病毒提供了一种新的抗病毒靶标设计策略。
