IRF3 and infection: Following treatment with 50 μg CHX ml−1, a concentration that inhibits both cellular and viral protein synthesis (Fig. 2a), p-IRF3 could be detected within 3 h of PIV5-VΔC vM2 infection, demonstrating that PIV5-VΔC vM2 infection activates IRF3 and therefore the IFN-induction cascade in the absence of either cellular or viral protein synthesis.