Characterization of MERS-CoV-MA-WT and MERS-CoV-MA-Δ4b in MRC-5 cells.

(A) Subconfluent monolayers of MRC-5 were infected with wild-type or Δ4b at a m.o.i. of 0.1 or 0.001. Culture supernatants were collected at 24, 48 and 72 h p.i. and titrated by plaque assay. The average of two independent experiments is represented. (B) The mRNA expression levels of genes related to the IFN or the pro-inflammatory responses were quantified by RT-qPCR in MRC-5 cells either mock-infected or infected with WT or Δ4b viruses at m.o.i. 1 and 24 h p.i. Error bars represent standard deviations of the mean (n = 3). Differences were analyzed by Student’s t test: *, p-value < 0.05; **, p-value < 0.01.