However, when A549 cells were pretreated with IFN, production of the five viral proteins that were measured, namely, the NS1 protein, the nucleoprotein (NP), and the three protein subunits of the viral polymerase (PB1, PB2, and PA), was severely reduced in WT Ud virus-infected cells, which was not the case in cells infected with the construct viruses (Fig. 2c), indicating that enhanced replication of the two construct viruses also occurred in high-MOI infections of IFN-treated A549 cells. The gene discussed is IFNA1; the disease is infection.