Fig. 2: Effects of drugs on SARS-CoV-2 replication and intracellular calcium oscillations.

a, Inhibition of SARS-CoV-2 replication. Vero E6 cells were treated with the indicated drug concentrations for 2 h, followed by the addition of SARS-CoV-2 (MOI 0.05). After 1 h, cells were washed and cultured in drug-containing medium for 48 h. Virus production in the culture supernatants was quantified by plaque assay using Vero E6 cells. Data are mean ± s.d.; n = 3. b, Representative frames (from of a total of 600) from a 12-h time-lapse movie of a co-culture of Vero cells expressing the GCaMP6s Ca²⁺ sensor and U2OS cells transfected with spike protein and mCherry. Arrowheads indicate Ca²⁺ oscillations in GCaMP6s–ACE2-expressing cells when fusing to spike-expressing cells. See Supplementary Video 4 for time-lapse movie. c, Ca²⁺ oscillations during syncytia formation. Representative frames (from of a total of 400) from a 12-h time lapse movie of spike-expressing Vero cells. Arrowheads indicate cells progressively fusing to a syncytium and show intense Ca²⁺ spikes. See Supplementary Video 5 for time-lapse movie (movie in the top left panel, labelled ‘DMSO’). d, GCaMP intensity over time. Vero cells were co-transfected with GCaMP6s and either a control or a spike-expressing vector and treated with the indicated drugs. Data are expressed as change in fluorescence (ΔF/F) over time (min); every line is 1 of at least 12 180-μm² regions of interest per condition, representing a group of 4 GCaMP-positive cells on average. See Supplementary Video 5 for representative movies.