Fig. 1: Attenuated virus replication of SARS-CoV-2 Omicron.

a–d, Cells were challenged with SARS-CoV-2 WT, Alpha, Beta, Delta, Omicron or Omicron(R346K) at a multiplicity of infection (m.o.i.) of 0.5 (for Calu3) or 0.1 (for Caco2 and VeroE6). a, Cell lysates were collected at the designated time points for quantifying the subgenomic RNA of the envelope gene (sgE). n = 7. The robustness of sgE production was quantified by AUC analysis. b–d, Infectious viral particles were titrated using median tissue culture infectious dose (TCID₅₀) assays in Calu3 (b), Caco2 (c) and VeroE6 cells (d). n = 4. e, The cell viability of VeroE6-TMPRSS2 cells infected with SARS-CoV-2 WT and other variants at 0.1 m.o.i. was quantified at the designated time points. n = 6. Data are mean ± s.d. from the indicated number of biological repeats. Statistical significance was determined using one-way analysis of variance (ANOVA) (a), two-tailed Student’s t-tests (b–d) and two-way ANOVA (e); where multiple comparisons were performed among different groups, P values were adjusted using Tukey’s multiple-comparison test; *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001; NS, not significant. Data were obtained from three independent experiments. Each data point represents one biological replicate.

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