Interaction of Newcastle disease virus V protein with EFTUD2 modulates MDA5 pathway to suppress viral replication

Elongation factor Tu GTP-binding domain-containing protein 2 (EFTUD2), a core component of U5 small nuclear ribonucleoprotein particles (snRNPs), recently emerged as a novel innate immune regulator. Although the Newcastle disease virus (NDV) V protein facilitates immune evasion, interactions between NDV and spliceosome components remain poorly characterized. Using immunoprecipitation-mass spectrometry (IP-MS), we identified EFTUD2 as an interacting partner of the NDV V protein. Co-immunoprecipitation (Co-IP) and confocal microscopy confirmed this interaction, which we mapped primarily to residues 116-825 of EFTUD2. EFTUD2 overexpression enhanced chicken MDA5 (chMDA5) splicing efficiency, upregulated interferon-stimulated genes (ISGs) and interferon-β (IFN-β) production, and consequently suppressed NDV replication. Conversely, siRNA-mediated EFTUD2 knockdown promoted viral replication. Notably, EFTUD2's regulation of chMDA5 splicing occurred specifically during NDV infection, suggesting that the V protein potentially activates EFTUD2's splicing function. These findings establish EFTUD2 as a critical host restriction factor against NDV and provide novel mechanistic insights into viral immune evasion and host defense.