Infection-induced gene expression levels of inflammatory cytokines such as Il6 and Tnf, type I (Ifna4 and Ifnb), and type III IFNs (Ifnl2/3) as well as ISGs such as Mx1, Isg15, and Stat1 peaked simultaneously with peak viral loads on day 2 p.i. in lungs and upper airways (Fig. 3 D and Fig. S2 I). Here, ISG15 is linked to infection.