Generation of viral cDNA clones and recovery of recombinant MERS-CoV and MERS-CoV-GFP.a, Schematic representation of MERS-CoV (upper panel) and MERS-CoV-GFP (lower panel) genome organization with 8 and 10 viral subgenomic overlapping cDNA fragments, respectively, used for TAR cloning. pT7, T7 RNA polymerase promoter; UTR, untranslated region; An, poly (A) tail; J represents assembly junction between two overlapping DNA fragments. 