Fig 4.

Type I IFN production in sera of TLR7^−/− and Myd88^−/− mice is similar to that in sera of WT mice early during infection. Twenty-four-day-old WT, TLR7^−/−, and Myd88^−/− mice were subcutaneously infected in the left rear footpad with 10³ PFU of RRV. At the indicated time points, mice were sacrificed by exsanguination and serum was collected. Serum was diluted 1:5 in medium and analyzed for the presence of type I IFN (IFN-α/β) by IFN bioassay as described in Materials and Methods. (A) Type I IFN production in sera of WT and TLR7^−/− mice. (B) Type I IFN production in sera of WT and Myd88^−/− mice (n = 3 to 5 mice/strain/time point).