Structural basis for DNA replication by the African swine fever virus polymerase.

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.