Fig. 3: Select RBD mAbs demonstrate ACE2 binding inhibition, neutralize across SARS-CoV-2 variants of concern, and demonstrate protection in vivo.

ACE2 inhibition by WRAIR RBD mAbs in a BLI-based assay. RBD mAbs were assessed for their ability to block hACE2 binding to a SARS-CoV-2 RBD or b S-2P. The half-maximal effective concentration (EC₅₀) in µg ml⁻¹ is indicated in parentheses. Cross-reactivity of mAbs were assessed for activity against SARS-CoV-2 VoCs and SARS-CoV-1, using c BLI, or d IC₅₀ values measured against pseudotyped virus. e Binding kinetics of WRAIR-5001 with SARS-CoV-2 WA-1, Delta, Omicron BA.1, Omicron BA.4/5, and SARS-CoV-1 RBDs, as measured by BLI. Additional kinetics values may be found in Supplementary Table 2. f In vivo protection study plan and design of prophylactic administration of RBD mAbs. RBD mAbs WRAIR-5001 and WRAIR-5021 were given at single dose of 10 mg/kg intravenously in K18-hACE2 transgenic mice, followed by challenge with SARS-CoV-2 Delta (B.1.617.2) intranasally 24 hours later (n = 13 animals/group). 5 mice from each group were sacrificed on day 2 for plaque reduction neutralization test (PRNT) assay, and surviving mice were measured for body weight changes and survival out to day 14. RBD mAb WRAIR-2125 was used a positive control, and the negative control was an IgG isotype Zika-specific mAb, MZ4. g Particle forming units (PFU) measured in the lungs or bronchoalveolar lavage (BAL) of mice on study day 2 (n = 5 animals/group). Error bars indicate the standard deviation. (****P < 0.0001 using ordinary one-way ANOVA compared to IgG isotype control, MZ4) h Percent loss of body weight out to study day 10 and i survival curves out to study day 14 (study end date). (****P < 0.0001 using ordinary one-way ANOVA compared to IgG isotype control, MZ4). Source data are provided as a Source Data file. The mouse image was created with BioRender.com.