FIG 5.

The activity for inhibition of IFN synthesis, but not the RNase activity, of E^rns is reduced in the absence of its C terminus. (A) A 300-bp dsRNA fragment from the 5′ UTR of BVDV strain Ncp7 was incubated in 100 mM Tris-acetate buffer in the presence of wt E^rns, E^rns lacking the C terminus (E^rns ΔC-term), or concentrated supernatant of cells transfected with the empty vector for 1 h at 37°C. RNA was separated on 1% agarose gels and visualized by UV light after staining with ethidium bromide. (B) E^rns was incubated on BT cells for 30 min before the cells were washed and incubated with 2 μg/ml poly(I·C) for 18 h at 37°C. Cytosolic extracts were assayed for Mx as described in the legend to Fig. 1. Typical results out of three independent experiments are shown. (C) Three independent replicates performed as described for panel B were quantified for the efficiency of E^rns inhibition of dsRNA-induced Mx expression by AIDA software, as described in the legend to Fig. 3, with the level of Mx expression induced by poly(I·C) alone being set equal to 100% (mean ± SD, n = 3).