To determine whether changes in abundance of IRF-dependent gene expression, as well as the increased IRF-driven gene transcription observed in response to rhMPV- ΔG infection, resulted from enhanced IRF-3 protein activation, we investigated IRF serine phosphorylation and nuclear translocation by Western blot analysis, using nuclear extracts from control and rhMPV-infected A549 cells (Fig. 4C). The gene discussed is IRF3; the disease is infection.