Fig. 6.

Sensitivity of MERS-CoV and SARS-CoV to PEG-IFN. Vero cells were incubated with 0–1000 ng PEG-IFN ml⁻¹ at t = −4, t = 0 and t = 4 h p.i. Cells were infected with 100 TCID₅₀ virus per well (a, b). At 2 days p.i., cells were examined for CPE. The effect of PEG-IFN treatment on CPE induced by SARS-CoV (a) or MERS-CoV (b) is shown. CPE was scored as none (0), mild (1), moderate (2), severe (3) or complete (4). (c, d) Viral genomes in the culture medium of virus-infected cells were determined by RT-PCR. The influence of PEG-IFN treatment on the viral RNA load [genome equivalents (gen. eq.) ml⁻¹] in the supernatants of cells infected with SARS-CoV (c) or MERS-CoV (d) is shown.