RESULTS
G-protein deficient VSV bearing C-terminal 21 aminoacid truncated Spike protein were packaged in HEK293T cell line (Figure 1 ). To fully eliminate ancestral VSV-G, Spike pseudoviruses were serially passaged in pmD2.SpikeCdel21 transfected Vero E6 cells.
Hydroxychloroquine (HCQ) effectively inhibits viral entry and has been proposed for prophylaxis/treatment of SARS-CoV-2 infection. Therefore, HCQ was used to display inhibition of pseudovirus entry and construction of reliable pseudovirus assays. Harvested VSV-ΔG-Sdel21 pseudotyped virus were analyzed for viral entry using HCQ (20-50 µM). Virus infectivity was decreased with increasing concentration of hydroxychloroquine based on percentage of GFP-positive cell(Figure 2A and 2B) . The number of GFP-positive cells in VSV-ΔG-Sdel21-infected Vero E6 cells were significantly reduced from 30% to 10% in highest concentration of HCQ compared to positive control (p<0.0001). Representative image of positive control was given in Figure 2S.