FIG. 1.

Infection with influenza virus induced significantly more IFN-λ than IFN-α. Cohorts of BALB/c wild-type (A) or IFNAR^−/− (B) mice (n = 4) were infected i.n. with 10⁴ PFU of influenza A/WSN/33, and BAL samples were harvested 24, 48, 72, or 96 h postinfection. Concentrations of IFN-α (black bars) and IFN-λ (white bars) were determined by ELISA. Data represent the means and standard errors of the means. (C) Results of an assay of IFN-α/β and IFN-λ2 antiviral activity on the mouse lung epithelial cell line MLE-15.