<p>Traditional antiviral strategies primarily rely on vaccines and virus protein-targeting drugs, which adopt a virus-targeting approach. However, the rapid mutation of viruses often leads to vaccine failure and drug resistance, highlighting the limitations of these conventional methods. Consequently, the development of novel broad-spectrum, host-targeting antiviral strategies has become a major research focus. Itaconate, an endogenous immunomodulatory metabolite, inhibits viral replication via post-translational modifications; however, its mechanism in suppressing viral endocytosis remains unclear. This study demonstrates that itaconate inhibits viral endocytosis by covalently modifying the Cys128 site of the adaptor-related protein complex 1 gamma 1 subunit (AP1G1), thereby providing a new target for host-directed antiviral drug development. It was found that itaconate binds to AP1G1 at Cys128, impairing its interaction with clathrin, which inhibits clathrin-mediated viral particle uptake and reduces cellular susceptibility to infection (i.e., the likelihood of cells being infected by viruses and undergoing infection). Furthermore, the natural product Licochalcone B was identified as targeting the same site as itaconate. In both BEAS-2B cell models and mouse infection models, Licochalcone B reduced pulmonary viral loads by over 95%. This study is the first to propose and validate the feasibility of inhibiting broad-spectrum viral infection by targeting AP1G1, elucidating a novel molecular mechanism of itaconate-mediated regulation, offering a new target for broad-spectrum antiviral drug development, and identifying Licochalcone B as a promising broad-spectrum antiviral agent.</p>