Figure 2.

Time course of reactivation of FMS₇–IFN-α2 upon incubation at 37°C, pH 7.4. FMS₇–IFN-α2 (1 mg/ml in PBS buffer, pH 7.4) was incubated at 37°C. Aliquots were withdrawn daily and analyzed for their antiviral potency to inhibit VSV-induced cytopathic effects in human WISH cells (see Materials and Methods). Results are expressed as percent of antiviral potency of the native cytokine. Half-maximal inhibition of cytopathic effect was obtained at 0.3 ± 0.03 pM IFN-α2. IFN-α2 derivative exhibiting half-maximal inhibition at a concentration of 30 ± 3 pM was considered as having 1% of the native antiviral potency.