Analysis of average infection-induced changes to total proteome abundance revealed that, in contrast to IAV, both IBV and IAVΔNS1 infections triggered a classical host IFN response consisting of several ISG products, including ISG15, ISG20, MDA5, MxA, IFIT1, and IFIT3 (Fig. 1 B–D and Datasets S1–S3). Here, ISG20 is linked to infection.