Fig. 2.

MERS-CoV-nsp5 inhibits IFN-β production at the level of IRF3 activation or downstream of it. BEAS 2b cells were co-transfected with IFN-β reporter plasmid, TK Renilla plasmid and increasing concentrations (200 & 400 ng/ml) of HA-tagged MERS-CoV-nsp5 or EV control together with plasmids expressing (A) RIG-I, (B) MAVS, (C) IKK-ε or (D) FLAG-IRF3-5D. At 48 h post transfection, cells were harvested and assayed for luciferase activity. The expression levels of the indicated proteins were analysed by western blotting. All luciferase assay experiments were performed at least three times and all data is shown as mean ± SEM. *P < 0.05, **P < 0.01 (Student’s t-test)