One key process in the life cycle of many viruses is the formation of dynamic organelles called viral factories. There is increasing evidence that some viral factories form via liquid-liquid phase separation (LLPS), including SARS-CoV-2, influenza and measles virus. Targeting the physicochemical process of phase separation may underlie discovery of novel, broad-spectrum antivirals, but this can only be realised by first understanding how viral factories form. Rotaviruses employ a similar mechanism of formation of replication factories via LLPS. Our research focuses on physicochemical properties of viral proteins to understand how they mediate assembly of viral factories, and in doing so, identify targets for future therapeutic intervention.