Fig. 6.

HDP-2P reduces the binding of an anti-ACE2 antibody and RBD of glycoprotein S to ACE2 receptor at 293T/ACE2 cells. a, b Inhibition of anti-ACE2 antibody binding to 293T/ACE2 cells by HDP-2P. 293T/ACE2 cells were incubated with (100 µg/ml) or without (control) HDP-2P for 30 min and stained using human phycoerythrin (PE) conjugated anti-mouse ACE2 antibody. MFI mean fluorescence intensity. c, d Cells were incubated with PBS (control) or HDP-2P. The RBD protein fused with human Fc was then added for 1 h. After washing, the binding of RBD was detected using a DyLight 650-conjugated secondary anti-human Fc antibody. e Representative RBD binding profile in control and HDP-2P-treated cells. The cell populations binding high (RBD^hi) and low (RBD^lo) amount of RBD are shown. The percentage of positive cells was determined using flow cytometry analysis. Significant difference was determined using a Student’s t test: *p˂0.05, **p˂0.01. Results are mean ± SD and are representative of at least three independent determinations