Figure 2. D614G substitution does not alter SARS-CoV-2 virion morphology and S protein cleavage pattern but change viral sensitivity to neutralizing antibodies.

A. Transmission electron microscopy image of WT and D614G virions on airway epithelial cell surface, scale bar: 200 nm. B. Scanning electron microscopy images of WT and D614G virions on airway epithelial cell surface, scale bar: 100 nm. C. Quantification of S protein on individual SARS-CoV-2 virion projections. The number of S protein on individual virion projections from different SEM images were quantify manually, n=20. D. Western blot analysis of SARS-CoV-2 virions washed from WT- or D614G-infected LAE culture surface at 72h. Each lane contains mixed sample from triplicated cultures. Full-length (S), S1/S2 cleaved and S2’ cleaved spike protein (upper panel) and nucleocapsid protein (lower panel) were probed. E. ID₅₀ values of 10 serum samples collected from D614-form Spike-vaccinated mice neutralizing WT- and D614G-nLuc viruses. F. Three representative neutralization curves of the mouse sera against both viruses. Summarized IC₅₀ values (G) and individual neutralization curves (H) of 6 human nAbs against both viruses. Data between the WT and D614G viruses in E and G are analyzed using paired t-test. N.S., not significantly different, p > 0.05; **, p < 0.01.