Figure 1.

RBD-binding antibodies are responsible for most of the neutralizing activity of human polyclonal plasma

(A) Change in binding of plasma to RBD and spike before and after depletion of RBD antibodies, measured by ELISA area under the curve (AUC). The dashed orange line is binding of pre-pandemic pooled sera collected in 2017 and 2018. Raw ELISA binding curves in Figure S1A.

(B) Neutralization titer 50% (NT50) of human plasma before and after depletion of RBD-binding antibodies. Legend is at left: filled and open circles are pre- and post-depletion samples, respectively, connected by a line. Orange indicates plasma for which we subsequently mapped mutations that reduce binding. The numbers at right indicate the percent of all neutralizing activity attributable to RBD-binding antibodies. Plasma are sorted in descending order of percent of neutralization due to RBD-binding antibodies, first by subject and then within subject. The dashed blue line is the limit of detection (NT50 of 20). Points on this line have an NT50 of 20, so the percent of neutralization due to RBD-binding antibodies may be an underestimate for these plasmas.

See Figure S1 and Table S1 for additional data including sample metadata, full ELISA and neutralization curves, and numerical values plotted here.