Patients with Coronavirus disease 2019 exhibit low expression of interferon-stimulated genes, contributing to a limited antiviral response. Uncovering the underlying mechanism of innate immune suppression and rescuing the innate antiviral response remain urgent issues in the current pandemic. Here we identified that the dimerization domain of the SARS-CoV-2 nucleocapsid protein (SARS2-NP) is required for SARS2-NP to undergo liquid–liquid phase separation with RNA, which inhibits Lys63-linked poly-ubiquitination and aggregation of MAVS and thereby suppresses the innate antiviral immune response. Mice infected with an RNA virus carrying SARS2-NP exhibited reduced innate immunity, an increased viral load and high morbidity. Notably, we identified SARS2-NP acetylation at Lys375 by host acetyltransferase and reported frequently occurring acetylation-mimicking mutations of Lys375, all of which impaired SARS2-NP liquid–liquid phase separation with RNA. Importantly, a peptide targeting the dimerization domain was screened out to disrupt the SARS2-NP liquid–liquid phase separation and demonstrated to inhibit SARS-CoV-2 replication and rescue innate antiviral immunity both in vitro and in vivo.

2019 年冠状病毒病患者表现出干扰素刺激基因的低表达，导致抗病毒反应有限。揭示先天免疫抑制的潜在机制和挽救先天抗病毒反应仍然是当前大流行中的紧迫问题。在这里，我们发现 SARS-CoV-2 核衣壳蛋白 (SARS2-NP) 的二聚化结构域是 SARS2-NP 与 RNA 进行液-液相分离所必需的，它抑制了 Lys63 连接的多聚泛素化和 MAVS 的聚集和从而抑制先天性抗病毒免疫反应。感染携带 SARS2-NP 的 RNA 病毒的小鼠表现出先天免疫力下降、病毒载量增加和高发病率。尤其，我们通过宿主乙酰转移酶鉴定了 Lys375 的 SARS2-NP 乙酰化，并报告了 Lys375 频繁发生的乙酰化模拟突变，所有这些突变都损害了 SARS2-NP 与 RNA 的液-液相分离。重要的是，筛选出一种靶向二聚化结构域的肽以破坏 SARS2-NP 液-液相分离，并证明它可以抑制 SARS-CoV-2 复制并在体外和体内挽救先天抗病毒免疫。