Fig. 2.

rSARS-CoV-2 spike E484 mutants display viral replication and entry kinetics similar to wildtype rSARS-CoV-2. Multicycle infection experiments in (A) Calu-3, (B) Vero E6, and (C) NCI-H1299 cells. Cells were infected with WT rSARS-CoV-2 or the indicated E484 mutants. As a control, we included a highly Vero E6 cell-adapted SARS-CoV-2 isolate (p100). Infectious particles sampled from culture supernatant at the indicated hpi were quantified by plaque titration. Shown are the combined data of two independent experiments, each performed in triplicate. Entry efficiency in (D) Calu-3 and (E) Vero E6 cells. Synchronized infections assays (MOI 1) were performed by virus inoculation on ice and a subsequent shift to 37 °C. Subgenomic messenger nucleocapsid RNA (sgRNA N) was quantified 1 and 4 h post infection. sgRNA N transcript levels were normalized to the housekeeping gene TBP. Significant differences in replication and entry efficiency between WT and rSARS-CoV-2 E484 mutants were determined by two-tailed Student t tests and are shown in Supplementary Table S1. MOI = multiplicity of infection; PFU = plaque-forming unit; inoc = inoculum; hpi = hours post-infection; WT = wild type