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. 2021 Nov 3;6:378. doi: 10.1038/s41392-021-00810-1

Fig. 3.

Fig. 3

N3113 is a non-ACE2 competing antibody that inhibits SARS-CoV-2 S protein-mediated membrane fusion. a Structural depiction of n3113, ACE2 (PDB entry 6LZG), CB6 (PDB entry 7C01) and S309 (PDB entry 6WS6) binding to SARS-CoV-2 RBD. RBD is represented as a blue surface. ACE2, n3113, CB6 Fab, and S309 Fab fragments are shown as cartoon colored in cyan, orange, pink and yellow, respectively. b Binding mode comparison of Y449 and Q493 in SARS-CoV-2 RBD (blue) with ACE2 (cyan) and n3113 (orange). Sidechains of RBD-Y449, RBD-Q493, n3113-Y58, n3113-N60, n3113-P61, n3113-S62, ACE2-E35, ACE2-D38, and ACE2-Q42 are shown as sticks. The hydrogen bonds are represented in black dashed lines. c N3113 does not compete with ACE2 on binding to trimeric spike. Trimeric spike is represented in surface colored the same as in Fig. 2g. The superposed ACE2 is presented as a cyan cartoon. d Competition of n3113.1, n3113.1-Fc, CB6, and S309 with ACE2 for SARS-CoV-2 RBD binding were measured by BLI. Immobilized SARS-CoV-2 RBD were saturated with antibodies (1 µM n3113.1 or 100 nM n3113.1-Fc, CB6, S309), followed by incubation of the sensors with the corresponding antibody in the presence of (red) or without (blue) 200 nM soluble ACE2. As a control, the immobilized RBD was balanced in buffer and incubated with the equal molar of ACE2 (black). The grams show binding patterns after antibody saturation. e Analysis of S protein attachment to HEK293T-ACE2 cells. HEK293T-ACE2 cells were stained with 10 µg/mL his-tagged SARS-CoV-2 spike proteins pre-incubated with isotype IgG, CB6, or n3113.1-Fc. The percentage of binding was measured by anti-histag PE and analyzed by FACS. The experiments were performed twice with similar results and a representative figure was shown. f N3113 inhibits SARS-CoV-2 S protein-mediated membrane fusion. Membrane fusion was indicated by the formation of syncytium at 48 h after incubation. No antibody was added in the mock group (S). 10 μM n3113.1, n3113.1-Fc, S309, and CB6 were added individually to 293T-S-GFP cells before the incubation. 293 T cells transfected only with GFP was used as control (no S)