FIG 5.
Replication kinetics of MERS-CoV on BHK cells expressing mutagenized DPP4s. (A) Humanized hamster DPP4 (blue circles) or hamsterized human DPP4 (red squares) was expressed on BHK cells. As a control, human DPP4 (red circles) was expressed on BHK cells. Twenty-four hours posttransfection, cells were inoculated with MERS-CoV using an MOI of 1 TCID50/cell. Supernatants were harvested at 0, 24, 48, and 72 hpi, and viral titers were determined by endpoint titration in quadruplicate in VeroE6 cells. Mean titers were calculated from three independent experiments. Error bars indicate standard deviations. (B) BHK cells were left untransfected (red) or transfected with DPP4 (blue) and stained 24 h posttransfection using anti-DPP4 (R&D) and an FITC-conjugated secondary antibody (Life Technologies). Samples were collected using an LSRII flow cytometer (BD Biosciences) and analyzed using FlowJo software.