FIG. 2.

Sustained type I IFN production upon THOV(ΔML) infection in vivo is dependent on IPS-1. (A) C57BL/6 mice (WT), MyD88^−/− TRIF^−/− mice, and IPS-1^−/− mice were inoculated i.p. with 2 × 10⁴ PFU of THOV(ΔML). Serum was collected at the indicated time points after immunization and analyzed for IFN-α by ELISA (n = 3 to 5). (B) C57BL/6 mice were i.p. inoculated with 2 × 10⁴ PFU of THOV(ΔML) or 2 × 10⁴ PFU of THOV(ΔML) which was UV irradiated (150 mJ/cm²) prior to infection. Serum was collected at the indicated time points after immunization and analyzed for IFN-α by ELISA (n = 3). (C) In parallel, survival of mice was monitored. (D) At 60 h postinfection mice were sacrificed, organs were homogenized, and virus titers were determined by plaque assays on Vero cells. <, not detectable. Data shown are representative of three independent experiments. Error bars indicate standard deviations. **, P < 0.01 ≥ 0.001 by one-factorial analysis of variance (WT compared to MyD88^−/− TRIF^−/− mice at 24 h postinfection and WT compared to IPS-1^−/− mice at 48 h after infection) and by a unpaired two-tailed t test (for panel B).