Figure 2.

Binding characteristics of bsAbs determined by single particle MP

(A) Mass photometry (MP) measurements of COVA IgG++ and IgG+- formats (A), in complex with soluble Wuhan-Hu-1 S protein. The mass histograms were fitted with Gaussian curves corresponding to each distinct assembly. The vertical dashed lines indicate the expected peak positions of each IgG-bound species. All measurements were performed with a 3:1 Ab:S ratio. Percentage values are derived from the normalized summation of two 120 s MP acquisitions.

(B) Fractional occupancies of Wuhan-Hu-1 S binding are summarized as heatmaps for IgG++ and IgG+- NAbs. The darkest blue color for each NAb represents its preferred binding stoichiometry.

(C and D) (C) MP measurements of bsAbs and corresponding cocktails to Wuhan-Hu-1 S and the corresponding heatmaps in (D).

(E and F) Binding of the bsAbs in comparison to the parental NAbs to SARS-CoV-2 Beta (E) and SARS-CoV (F) S proteins was assessed and summarized as a table of occupancies.

See also Figures S2 and S3.