FIG 5.

Characterization of growth kinetics of rMERS-nsp14-E191D and its sensitivity to 5-FU treatment. Vero cells (A) or HuH7 cells (B) were infected at an MOI of 3, supernatant was harvested at the indicated time points, and viral progeny titers were measured by plaque assay from two independent experiments using duplicates (n = 4; values are means ± standard deviations [SD]). (C) Plaque phenotype in HuH7 cells of rMERS-CoV nsp14-E191D and wt control in the absence or presence of the mutagenic agent 5-FU. (D) Dose-response curve of wt and E191D mutant MERS-CoV in the presence of 5-FU concentrations up to 400 μM (MOI, 0.1; n = 4; means ± SD). Statistical significance of the difference with wt virus at each time point (A and B) or concentration (D) was assessed by paired t test. *, P < 0.05; **, P < 0.005.