FIG. 1.

Effect of poly (I:C) and type I IFNs on RVFV replication. (A) Survival of mice infected with wt RVFV in vivo. C57BL/6 mice (age 6 to 8 weeks, n = 6 per group) were injected intraperitoneally with PBS (control) or 100 μg of poly(I:C) for 12 h and then infected intraperitoneally with 10³ PFU wt RVFV (strain ZH548). Uninfected control mice injected with PBS did not display any signs of disease (data not shown). (B) Type I IFNs act as antiviral cytokine against RVFV in vitro. Vero cells were treated with IFN-α (1,000 U/ml), IFN-β (1,000 U/ml), IFN-γ (500 U/ml), or TNF-α (500 ng/ml) and then infected with wt RVFV (MOI = 0.01). Cytokines were replenished for the incubation period of 24 h, after which the amount of virus in the supernatant was determined by plaque assay on IFNAR^−/− cells.