MERS coronaviruses from camels in Africa exhibit region-dependent genetic diversity

Chu, Daniel K. W.; Hui, Kenrie P. Y.; Perera, Ranawaka A. P. M.; Miguel, Eve; Niemeyer, Daniela; Zhao, Jincun; Channappanavar, Rudragouda; Dudas, Gytis; Oladipo, Jamiu O.; Traoré, Amadou; Fassi-Fihri, Ouafaa; Ali, Abraham; Demissié, Getnet F.; Muth, Doreen; Chan, Michael C. W.; Nicholls, John M.; Meyerholz, David K.; Kuranga, Sulyman A.; Mamo, Gezahegne; Zhou, Ziqi; So, Ray T. Y.; Hemida, Maged G.; Webby, Richard J.; Roger, Francois; Rambaut, Andrew; Poon, Leo L. M.; Perlman, Stanley; Drosten, Christian; Chevalier, Veronique; Peiris, Malik

Phenotype of ΔORF4b EMC Virus. To directly address whether the ORF4b deletion affects viral replication competence, we used reverse genetics to derive a recombinant EMC virus carrying the ORF4b deletion (rgEMCΔ4b) and compared this with an isogenic recombinant wild-type virus (rgEMC-WT). Replication competence of rgEMCΔ4b virus in Calu-3 cells infected at an MOI of 0.01 was not significantly different from rgEMC-WT virus as assessed by infectious virus titers at 24 h post infection, although it was reduced at 48 and 72 h post infection (Fig. 4A) . In Calu-3 cells infected at an MOI of 2.0, viral UpE gene expression was comparable or lower in rgEMCΔ4b-infected cells (Fig. 4B ), but the expression of IFN-β, IFN-λ1/IL-29, CXCL10 (IP-10), ISG15, Mx1, and TNF-α was significantly higher (Fig. 4C and Fig. S8 ).