Inoculation of IRF3/7-/- and C57BL/6 mice (with 2 x 104 CCID50 of virus) by intranasal and oral routes showed that the IFNα/β response-deficient IRF3/7-/- mice are more susceptible to infection via mucosal surfaces than C57BL/6 mice, with viraemias not detected or at the limit of detection (2 log10CCID50) in C57BL/6 mice (Fig 3). This evidence concerns the gene IRF3 and infection.