Fig. 5.

Spike shedding induced by anti-SARS-CoV-2 antibody binding. (A) Selected scFv-Fcs were tested in a spike shedding experiment using 293T cells stably expressing the SARS-CoV-2 spike. Percent change is relative to the median fluorescence signal for each sample at the 5 min time point, and antibody traces are colored based on their epitope sub-bins. Bin 2 antibodies Ab 2-7 and Ab 28 do not lead to shedding of the spike as seen by the increase in fluorescent signal over time. Antibodies in Bin 3E (Abs 17, 19, 35) trigger minimal to low shedding (green traces), whereas Abs in Bin 3C (Abs 14, 18, 27, 38) all lead to significant levels of spike shedding. Ab 12 (Bin 3A) leads to the most significant amount of shedding, whereas sub bin member Ab 7 induces significantly less shedding. (B) Selected scFv-Fcs were tested against their respective IgGs. Abs 12 and 38 display similar levels of spike shedding as an IgG and scFv-Fc, correlating to a minimal change in IC50 in in vitro virus neutralization assays. Abs 14, 27 and 29 show pronounced decreases in the amount of spike shedding in the IgG compared with the original scFv-Fc, providing a rational to their drastic loss of neutralization efficacy seen with in vitro neutralization assays.