Fig. 4: Synergistic neutralization mechanisms of P17 and H014.

a SPR kinetics of competitive binding of P17 and ACE2 to SARS-CoV-2 S. SARS-CoV-2 S was immobilized onto the sensor. P17 was first injected, followed by ACE2 (upper), vice-versa ACE2 was injected first and then P17 (lower). The control groups are depicted by black curves. b Pre- and post-adsorption inhibition assays. Amounts of virus detected by RT-PCR when exposed to P17 before (upper) and after (lower) the virus was allowed to attach to cells. Values are mean ± SD. Experiments were repeated in duplicate. c Clashes between P17 Fab and ACE2 upon binding to SARS-CoV-2 S. P17 Fab is represented as surface; SARS-CoV-2 S trimer and ACE2 are shown as ribbon. d P17 inhibits S protein-mediated cell–cell fusion. 293T cells were transfected with SARS-CoV-2 S-GFP protein, co-cultured with Vero E6 cells in the absence or presence of 100 μg/mL or 1 μg/mL or 0 μg/mL P17. Images were taken after 48 h. Scale bar, 100 μm. e Different concentrations of P17 block the ACE2-mediated fusion of SARS-CoV-2 with liposomes. Low concentration of H014 has synergistic effects on P17 blocking. Liposomes were loaded with the fluorescent dye calcein with self-quenching concentrations. Fusion of SARS-CoV-2 with liposomes occurred in the presence of both ACE2 and trypsin, perturbing the bilayer resulting in the release of calcein and a consequent increase in fluorescence. 10% Triton X-100 treatment was used to achieve 100% calcein leakage. The data are from three independent experiments.