NMI suppresses BEFV replication and is degraded by BEFV-induced NIX-dependent selective autophagy

N-Myc interactor (NMI) functions in various viral infections and serves as a regulatory component of innate immune signaling, its function during bovine ephemeral fever virus (BEFV) infection remains to be elucidated. Herein, we establish that NMI attenuates BEFV replication in BHK-21 and MDBK cells, as evidenced by diminished viral nucleoprotein gene expression and viral loads in NMI-overexpressing cells, whereas NMI depletion significantly enhances viral replication. Further analyses reveal that NMI augments type I interferon (IFN-I) pathway activation via the transcriptional induction of Ifnb and downstream effectors, namely Isg15, Ifitm3, Mx1, Isg54 and Isg56. At the molecular level, NMI engages with IRF3, facilitating its phosphorylation and subsequent nuclear import, consequently potentiating IFN-I-mediated immune activation. Notably, BEFV infection counteracts this antiviral defense by inducing autophagy, resulting in time-dependent autophagic degradation of NMI. Further analysis demonstrates that BEFV-mediated NMI degradation occurs selectively through the autophagy receptor NIP3-like protein X (NIX), as pharmacological inhibition of autophagy or NIX knockout abrogates NMI degradation, while NIX overexpression accelerates NMI turnover. Collectively, our results delineate a novel molecular mechanism whereby NMI restricts BEFV replication through the IRF3-IFN axis, while BEFV evades this restriction via NIX-mediated selective autophagy. These observations furnish critical insights into NMI function and the dynamic crosstalk between host antiviral defenses and viral immune evasion mechanisms, which may lay the groundwork for the rational design of antiviral therapeutics.