VIROLOGY: Weapons of Mutational Destruction

The viral accessory protein Vif is required for the production of infectious virions by cells that do not normally permit viral replication to take place. In their Perspective, KewalRamani and Coffin discuss an exciting cluster of recent papers that identify a new viral mutagenic factor called APOBEC3G, which counteracts Vif's ability to enable viral replication in nonpermissive cells.