Assays

A549 cells were seeded in 96-well plates at a density of 2 × 104 cells per well. The following day, virus stocks were serially diluted in DMEM containing 2% FBS (2% DMEM), and cells were inoculated with dilutions in triplicate at 37°C for 2 h. After the incubation, cells were overlaid with DMEM supplemented with 1% carboxymethylcellulose (Fisher Scientific), 2% FBS, 10 mM HEPES, and 1× penicillin/streptomycin. At 48 hpi, the methylcellulose overlay and medium were removed, and cells were fixed ...