ASFV MGF110-7L Inhibits eIF4G1 Expression via Endoplasmic Reticulum Stress to Block Host Translation.

African swine fever virus (ASFV) is a highly contagious and lethal double-stranded DNA virus that relies on host cellular translation machinery for replication and immune evasion. The multigene family 110 (MGF110) contains several members with incompletely defined functions. Here, the role of MGF110-7L in host translation regulation was investigated in HEK-293T and PK15 cells. Ribopuromycylation assays demonstrated that MGF110-7L expression resulted in potent, dose- and time-dependent inhibition of nascent polypeptide synthesis. Western blotting revealed a selective reduction in eIF4G1 protein abundance, with no significant changes in eIF4G2, eIF4E, and eIF4A, while eIF4G1 mRNA levels remained unaffected, indicating post-transcriptional regulation. Overexpression of eIF4G1 partially rescued translation suppression. MGF110-7L also decreased eIF4B phosphorylation and activated the PERK/eIF2α pathway, consistent with the induction of endoplasmic reticulum (ER) stress. ER stress promoted stress granule (SG) formation and enhanced eIF4G1 association with the SG marker G3BP1. The inhibitor assays demonstrated that the suppression of eIF2α phosphorylation by ISRIB restored the abundance of eIF4G1 protein. In addition, the downregulation of eIF4G1 was reversed by the inhibition of autophagy using bafilomycin A1, indicating an SG-linked autophagy-lysosome degradation pathway. Co-immunoprecipitation assays confirmed increased eIF4G1-G3BP1 interaction, but no direct binding between MGF110-7L and eIF4G1. This work provides the first experimental evidence that an ASFV protein, MGF110-7L, suppresses cap-dependent translation through SG-mediated autophagic degradation of eIF4G1, thereby revealing a previously unrecognized mechanism of ASFV translational control. These findings not only extend current understanding of ASFV-host interactions but also suggest potential molecular targets for antiviral strategies and rational vaccine design.