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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 study has 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 PA, PB1, PB2, and also with 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. IMPORTANCE 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.

Production of type I IFN is pivotal for the cellular antiviral immunity. Virus infection leads to the activation of transcription factor IRF3 and subsequent production of type I IFN to eliminate viral infection.

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In Fig. 7B, the IP (Flag)/HA panel (2nd image from the top) is an inadvertent duplicate of the Lysate/HA panel (2nd image from the bottom). The corrected IP (Flag)/HA image is shown below. The authors apologize for any inconvenience caused. This correction does not change the scientific conclusions of the article.