FIG 3.

DPP4 ortholog glycosylation knockout mutants. (A) Neither wild-type nor glycosylation knockout (−gly) DPP4 molecules for ferret (fDPP4), hamster (haDPP4), or guinea pig (gpDPP4) support infection by MERS-CoV. (B) Successful removal of glycosylation is supported by an ∼2.5-kDa downward shift seen via Western blotting. The top blot represents DPP4, and the bottom blot represents β-actin as a control. (C) Fluorescent cell counts from MERS-CoV infection utilizing various DPP4 orthologs and their respective glycosylation knockout mutants. Cells were infected at an MOI of 0.1, and numbers of infected cells were counted at 72 hpi. The level of each DPP4 ortholog was measured in triplicate. Only hDPP4 had levels of infection significantly higher than those seen in the absence of DPP4 (*, P < 0.05 [Student's t test]). The remaining DPP4 orthologs and glycosylation knockouts had infection levels that were not significantly different from those seen in the absence of DPP4. Error bars indicate mean values ± 1 standard deviation.