Figure 4. STAT1 is required for ISG induction and resistance on influenza infection of 129 mice.

(a,b) STAT1−/−(129), IFNαβR−/−(129) and 129 epithelial cell cultures were infected with X31 at a MOI of 1. At 24 h post infection upregulation of (a) Oasl2, STAT2, IRF9, Ifi203, (b) IL-28 (IFNλ) mRNA and replication of X31 was assessed by RT–PCR. (c) STAT1−/−(129) (crossed circles), IFNαβR−/−(129) (filled triangles) and 129 mice (open triangles) were infected i.n. with 800 TCID₅₀ (upper panels) or 80 TCID₅₀ (lower panels) of X31. Weight loss and survival were recorded throughout infection. Graphs show mean±s.e.m. and are representative of two independent experiments where n=5 for qPCR and n=6 for weight loss and survival. 129:STAT1−/−(129) * and IFNαβR−/−(129):STAT1−/−(129) ^○, where **** or ^○○○○P<0.00001, ** or ^○○P<0.001, *P<0.01 by 2-way ANOVA (weight loss), Log-rank (Mantel-Cox) Test (survival) or Mann–Whitney test (RT–PCR quantification). The symbols on the right of graphs indicate statistical significance of the whole curve, as tested by two-way ANOVA.