Abstact

African swine fever virus (ASFV) devastates swine herds and lacks widely available antivirals. We show that the ASFV DNA polymerase beta (Pol β; gene G1211R) localizes to viral replication factories and is required for viral replication. Cryo-electron microscopy structures of Pol β in apo and double-stranded DNA (dsDNA)-bound states reveal pronounced conformational flexibility that enables transitions between functional states. Binding to dsDNA promotes higher-order oligomerization that is essential for catalytic activity, as demonstrated by structure-guided mutagenesis and biochemical assays. These findings define the structural basis of ASFV genome synthesis, highlight the functional significance of Pol β during viral replication, and provide a framework for polymerase-targeted antiviral discovery.