State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.
Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, Hubei, People's Republic of China.
J Virol. 2020 Dec 22;95(2). doi: 10.1128/JVI.01391-20.
The viral ribonucleoprotein (vRNP) of the influenza A virus (IAV) is responsible for the viral RNA transcription and replication in the nucleus, and its functions rely on host factors. Previous studies have indicated that eukaryotic translation elongation factor 1 delta (eEF1D) may associate with RNP subunits, but its roles in IAV replication are unclear. Herein, we showed that eEF1D was an inhibitor of IAV replication because knockout of eEF1D resulted in a significant increase in virus yield. eEF1D interacted with RNP subunits polymerase acidic protein (PA), polymerase basic 1 (PB1), polymerase basic 2 (PB2), and also with nucleoprotein (NP) in an RNA-dependent manner. Further studies revealed that eEF1D impeded the nuclear import of NP and PA-PB1 heterodimer of IAV, thereby suppressing the vRNP assembly, viral polymerase activity, and viral RNA synthesis. Together, our studies demonstrate eEF1D negatively regulating the IAV replication by inhibition of the nuclear import of RNP subunits, which not only uncovers a novel role of eEF1D in IAV replication but also provides new insights into the mechanisms of nuclear import of vRNP proteins. Influenza A virus is the major cause of influenza, a respiratory disease in humans and animals. Different from most other RNA viruses, the transcription and replication of IAV occur in the cell nucleus. Therefore, the vRNPs must be imported into the nucleus for viral transcription and replication, which requires participation of host proteins. However, the mechanisms of the IAV-host interactions involved in nuclear import remain poorly understood. Here, we identified eEF1D as a novel inhibitor for the influenza virus life cycle. Importantly, eEF1D impaired the interaction between NP and importin α5 and the interaction between PB1 and RanBP5, which impeded the nuclear import of vRNP. Our studies not only reveal the molecular mechanisms of the nuclear import of IAV vRNP but also provide potential anti-influenza targets for antiviral development.
甲型流感病毒（IAV）的病毒核糖核蛋白（vRNP）负责病毒 RNA 在细胞核中的转录和复制，其功能依赖于宿主因子。先前的研究表明，真核翻译延伸因子 1 三角洲（eEF1D）可能与 RNP 亚基结合，但它在 IAV 复制中的作用尚不清楚。本文中，我们发现 eEF1D 是 IAV 复制的抑制剂，因为 eEF1D 的敲除导致病毒产量显著增加。eEF1D 以 RNA 依赖性的方式与 RNP 亚基聚合酶酸性蛋白（PA）、聚合酶碱性 1（PB1）、聚合酶碱性 2（PB2）以及核蛋白（NP）相互作用。进一步的研究表明，eEF1D 阻碍了 IAV 的 NP 和 PA-PB1 异二聚体的核输入，从而抑制了 vRNP 的组装、病毒聚合酶活性和病毒 RNA 的合成。总之，我们的研究表明 eEF1D 通过抑制 RNP 亚基的核输入来负调控 IAV 的复制，这不仅揭示了 eEF1D 在 IAV 复制中的新作用，也为 vRNP 蛋白的核输入机制提供了新的见解。甲型流感病毒是导致流感的主要原因，流感是人和动物的呼吸道疾病。与大多数其他 RNA 病毒不同，IAV 的转录和复制发生在细胞的细胞核中。因此，vRNP 必须被导入细胞核中进行病毒转录和复制，这需要宿主蛋白的参与。然而，IAV 与宿主相互作用的核输入机制仍知之甚少。在这里，我们将 eEF1D 鉴定为流感病毒生命周期的一种新型抑制剂。重要的是，eEF1D 破坏了 NP 与 importin α5 之间以及 PB1 与 RanBP5 之间的相互作用，从而阻碍了 vRNP 的核输入。我们的研究不仅揭示了 IAV vRNP 核输入的分子机制，也为抗病毒药物的开发提供了潜在的抗流感靶点。
