Evaluating MERS-CoV Infection in Huh7 and MRC5 Cells

Huh7 cells (JCRB, No. JCRB0403) were infected with wt or modified rMERS-CoV at a multiplicity of infection (MOI) of 0.01 or 5, to analyze multi- or single-cycle infections, respectively. MOI 0.01 or 1 was used to infect MRC5 cells (CCL-171, ATCC). The rMERS-CoV inoculum was prepared in PBS containing DEAE (0.005% w/v) and 2% FCS, which was put on the cells after removing the medium. Inocula were removed after 1 h at 37 °C and EMEM supplemented with antibiotics, and 2% FCS was added to the cells. Following a high-MOI infection, cells were first washed three times with PBS before adding medium. Supernatants were harvested at various time points and rMERS-CoV titers were determined by plaque assay on Huh7 cells (JCRB, No. JCRB0403). Significance relative to the wt virus control was calculated using an unpaired Student’s t test and P values of less than 0.05 were considered statistically significant.