FIG. 8.

The activity of the ISP is not due to dsRNA. Murine IFN-γ (100 U), ISP (2 μg), or poly(I)-poly(C) (5 μg) were used untreated or subjected to digestion for 60 min at room temperature with either 50 U of DNase, 12.5 U of RNase, or 15 min of boiling. These treated compounds were added to primary murine spleen cells for 24 h. The cultured media were then transferred to MKF (which are not responsive to the ISP) for 24 h prior to the addition of VSV. Cells were monitored for cell survival and stained with crystal violet ∼18 h after infection. Each bar represents the mean of triplicate wells.