FIG 8

CEACAM5 overexpression does not confer infectivity to nonpermissive cells on MERS-CoV but enhances MERS-CoV entry into permissive cells. (A and C) To verify the role of CEACAM5 in MERS-CoV entry, human CEACAM5 was overexpressed in BHK21 cells or AD293 cells. The cells were then challenged with MERS-CoV at an MOI of 1 for 2 h at 37°C. After 2 h, the cells were washed extensively and harvested for qPCR analysis. (B and D) To verify the role of CEACAM5 in MERS-CoV attachment, human CEACAM5-expressing BHK21 cells or human CEACAM5-expressing AD293 cells were challenged with MERS-CoV at an MOI of 1 for 2 h at 4°C. The cell lysates were then harvested for qPCR analysis. DPP4- and empty-vector (pcDNA3.1)-expressing BHK21 cells were included as controls. The data are represented as means and standard deviations of the results of three independent experiments. The results from the human DPP4-, human CEACAM5-, and empty-vector-overexpressing samples were compared with those of the mock-treated samples. Statistical analyses were carried out using Student's t test. Statistical significance is indicated by the asterisks (P < 0.05).