Figure 4.

47D1 blocks spike-mediated membrane fusion

(A) 47D1 or 28D5 were mixed with RBD-AF647 at a molar ratio of 2:1 and incubated with HeLa-ACE2 cells. SARS-CoV-2 RBD binding of HeLa-ACE2 cells was quantified by flow cytometry.

(B) HeLa-ACE2 cells were incubated with biotinylated RBD, washed, and fixed with PFA to crosslink RBD and ACE2. Those cells were then incubated with 47D1 or 28D5, followed by incubation with BV421-anti-human IgG1 to detect antibody that bound to ACE2-interacting RBD on HeLa cells.

(C) SARS-CoV-2 RBD was captured on anti-HIS biosensors and incubated with indicated antibodies, followed by incubation with ACE2 or CR3022 to determine the competition for binding sites on RBD between indicated antibodies, ACE2, and CR3022.

(D) STORM images of virions on HeLa-ACE2 cell surface as detected by a SARS-CoV-2 spike S2 antibody.

(E) FarRed-labeled 293T-spike cells were incubated with indicated neutralizing antibodies for 30 min, mixed 1:1 with CFSE (5-(and 6)-carboxyfluorescein diacetate, succinimidyl ester)-labeled HeLa-ACE2 for 30 min at 37°C, and imaged with a fluorescence microscope.

Data are representative of two to three independent experiments. See also Figure S2.