Fig. 1.

Kinetics of MERS-CoV replication in Vero and Huh7 cells. Vero and Huh7 cells were infected with MERS-CoV (m.o.i. of 5). (a) Hybridization analysis of viral mRNAs isolated from MERS-CoV-infected cells using an oligonucleotide recognizing the viral genome and all sg mRNAs. Additional minor bands of ~3 and ~4 kb were observed (*) and may represent additional viral mRNA species that remain to be studied in more detail. However, the corresponding positions in the ORF4a/b and ORF5 coding regions do not contain a canonical core TRS sequence (AACGAA; van Boheemen et al., 2012) that might provide a direct explanation for their synthesis. (b) Analysis of the relative molarities of viral genome and each of the sg mRNAs (% of total viral mRNA). mRNA sizes were calculated on the basis of the TRS positions in the viral genome sequence (van Boheemen et al., 2012). Phosphorimager quantification was performed on the gel lanes with the RNA samples isolated from Vero cells at 10, 13 and 24 h p.i. (Fig. 1a; lanes 3–5, respectively; mean±sd). (c) Release of infectious MERS-CoV progeny into the medium of infected Vero or Huh7 cells at the indicated time points, as determined by plaque assay (mean±sd; n = 4).