IFNB1 and infection: Notably, RGDA/Q112D viruses harboring Q4R or G94D/G116R mutations efficiently replicated in both untreated and IFN-β-treated cells (Fig. 3I), suggesting that either the Q4R mutation or the G94D/G116R mutation is sufficient to confer IFN-β resistance to the RGDA/Q112D background during spreading infection.