Figure 4.

rVSV-SARS-CoV-2-S_Met1D614G∆21 replicates slowly but can be used to characterize S dependent entry. (A) Schematic of the engineered genome containing either the VSV-G or the SARS-CoV-2-S_Met1D614G∆21. Both include the nano-luciferase-P reporter gene after the glycoprotein. Multi-cycle replication curves (MOI 0.01) in both Vero and Calu3 cells using rVSV/G (B) or rVSV/S_Met1D614G∆21 (C). Luciferase levels were monitored in live cells after infecting cells with rVSV/G (D) or rVSV/S_Met1D614G∆21 (E). In the indicated samples, ammonium chloride (NH₄Cl) was added at the time of infection to establish the background within the assay. (F) Specific infectivity of viral particles was quantified by comparing the number of viral genomes within the sample to the infectious titers. rVSV/G samples are labeled G and rVSV/S_Met1D614G∆21 samples are labeled S. (G) Real-time neutralization assay. rVSV/S_Met1D614G∆21 was pre-incubated with decreasing concentrations of a neutralizing antibody (40592-R001, Sino Biological). The virus antibody mixture was added to Vero cells for 1.5 h at 37 °C. The inoculum was then removed, and luminescence was measured every 10 min over the course of the experiment. Data shown are the averages and SEM of three independent experiments performed in duplicate. **, p < 0.01.