African Swine Fever Virus Protein B263R Inhibits Autophagy by Promoting Proteasomal Degradation of Beclin1

African swine fever (ASF) is a highly contagious viral disease that affects both domestic and wild pigs, leading to substantial economic losses in the swine industry. However,the precise role of ASFV-encoded viral protein in viral replication and disease has remained elusive. In our study, we elucidated that B263R inhibited autophagy by interacting with Beclin1. Mechanistically, the binding of B263R to Beclin1 promotes its degradation through the mediation of K48-linked ubiquitination at site K31. Notably, the knockdown of Beclin1 mitigated the effect of B263R on reducing the levels of LC3-II, thus further affirming the pivotal role of Beclin1 in B263R-mediated autophagy inhibition. The proliferation of recombinant adenovirus inherently expressing B263R significantly decreased, underscoring the inherent role of B263R-mediated autophagy in virus replication. These findings shed light on the molecular mechanisms employed by ASFV to evade host cell autophagic defenses and offered potential targets for therapeutic interventions against ASFV infection. IMPORTANCEUnderstanding the mechanisms underlying the evasion of host cellular defenses by the African swine fever virus (ASFV) is of pivotal significance owing to its profound impact on the global swine industry. The precise functional roles of ASFV proteins in virus replication and disease remain incompletely characterized. In this study, it is demonstrated that a specific ASFV protein, B263R, acts to inhibit autophagy by interacting with Beclin1, thereby facilitating its degradation. The elucidation of this molecular pathway not only advances our comprehension of ASFV pathogenesis but also furnishes potential targets for therapeutic interventions against ASFV infection. By unraveling the intricate interplay between ASFV and host cell autophagy, this scholarly endeavor contributes invaluable insights to the development of strategies aimed at mitigating the spread of ASFV and minimizing its adverse repercussions on the swine industry.