FIG 7

CEACAM5 is an attachment factor for MERS-CoV. (A and B) To assess whether CEACAM5 is important for MERS-CoV entry, human CEACAM5 was overexpressed in BHK21 cells. Human CEACAM5-expressing BHK21 cells were then challenged with MERS-CoV at an MOI of 5 for 2 h at 37°C. The inoculum was replaced with culture medium, and the cells were incubated for another 4 h before being harvested for flow cytometry. (C and D) To assess whether CEACAM5 is important for MERS-CoV attachment, human CEACAM5-expressing BHK21 cells were challenged with MERS-CoV at an MOI of 30 for 2 h at 4°C before being harvested for flow cytometry. Human DPP4-expressing BHK21 cells were included as controls for both entry and attachment assays. (B and D) The data are represented as the percentages of MERS-CoV NP-positive BHK21 cells after infection with or without DPP4/CEACAM5 overepression. The means and standard deviations were derived from the results of three independent experiments. Statistical analyses were carried out using Student's t test. Statistical significance is indicated by the asterisks (P < 0.05).