IFNB1 and infection: IFNβ mRNA was detectable in total spleen lysate (Figure 5A) and in CD11c+ cells of Lm-infected mice (Figure 5B) at only 24 hr p.i. In contrast, in vivo infection with E. coli induced IFNβ production at an earlier stage as IFNβ gene induction occurred at 4 hr and 8 hr p.i. (Figure 5C).