Figure 4  Performance of monoclonal antibody 1A9 for detection of (A) S protein in a sandwich ELISA format and (B) SARS-CoV-2 infected cells
HA: haemagglutinin; H7N7: influenza A (H7N7); mAb: monoclonal antibody; MOI: multiplicity of infection; OD: optical density; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2.
A. Sandwich ELISA assay to determine mAb 1A9 ability to pair with the human mAb CR3022 for the detection of a His-tagged SARS-CoV-2 spike protein. 1A9 and CR3022 were used as capture and detector antibodies respectively. His-tagged HA protein of influenza A (H7N7) virus was used as a negative control. Averaged readings across three replicate experiments are presented. Error bars represent standard deviations across the three replicate experiments. Asterisks indicate significantly increased binding of the antibody pairs to SARS-CoV-2 S protein compared to influenza A (H7N7) HA at p < 0.05.
B. Vero E6 cells were mock-infected (left panel) or infected with SARS-CoV-2 (right panel; MOI of 1). At 24 hour post infection, the cells were stained with mAb 1A9 (5 µg/mL) followed by Alexa Fluor 488-conjugated secondary antibody (green). Nuclei were counterstained with 4′,6-diamidino-2-phenylindole (DAPI; blue).