Figure S1.

Specificities of the antibodies used in this study, related to Figures 1 and 3

(A) The expression constructs used to analyze the specificity of the anti-spike antibodies. (B) The plasmids encoding the full-length spike, Flag-NTD-TM, Flag-RBD-TM, and Flag-S2-TM were cotransfected separately with a GFP vector into HEK293T cells. The transfectants were then stained with the indicated antibodies. The antibodies bound to the transfectants were detected with APC-labeled secondary antibodies. The fluoresce intensities of APC on the GFP-expressing cells are shown (red line). Control stainings were shown as shaded histogram. (C) The plasmids expressing the wild-type spike protein and the D614G mutant were cotransfected separately with a GFP vector into HEK293T cells. The transfectants were stained with the anti-NTD infectivity-enhancing antibody COV2-2490 and anti-NTD non-enhancing antibody 4A8. The fluorescence intensities of APC on the GFP-expressing cells are shown (red line). Control stainings were shown as shaded histogram. (D) Parental HEK293T cells and ACE2-transfected HEK293T cells were stained with anti-ACE2 mAb (red line). Control stainings were shown as shaded histogram.