Figure 1
From: Unbiased approach to identify and assess efficacy of human SARS-CoV-2 neutralizing antibodies
Rapid Discovery of Neutralizing Antibodies. (A) The G-MAB phage display library was panned for SARS-CoV-2 Spike S1 subunit-binding scFv fragments. Following confirmation of binding activity and blocking of S1:ACE2 interactions by candidate scFvs, the most potent of these candidates were converted to IgG1 antibodies bearing the LALA Fc modification. Candidate nAbs were characterized for binding of Spike S1 subunit and neutralization of related clinical SARS-CoV-2 isolates. Affinity maturation of potent nAbs was carried out in parallel to biophysical profiling, cell line development, and evaluation of protective efficacy for the parental nAbs, S1D2 and S7E3 to yield STI-2020 and STI-5041, respectively. Artwork credit: William SooHoo. (B) Affinity measurements of STI-2020 and STI-5041 for Spike S1 domain from the following isolates and VOCs: USA/WA-1/2020(WA-1) isolate, D614G 2020001 isolate, B.1.1.7 VOC (Alpha), B.1.351 VOC (Beta). The antibody affinities were measured using SPR on a BIAcore T200 instrument using a 1:1 binding model. (C) Spike protein derived from the WA-1 and 2020001 (D614G) SARS-CoV-2 isolates were independently expressed on the surface of HEK 293 cells. Serially-diluted STI-2020 or STI-5041 were assayed for Spike protein binding by flow cytometry. To quantify antibody binding, mean fluorescent intensity was measured for each dilution tested and the EC50 value was calculated for each nAb. Representative replicate experiments are shown. (D) STI-2020 and STI-5041 were evaluated in neutralizing test for potency against SARS-CoV-2 USA/WA-1/2020, 2020001 (D614G), B.1.1.7 VOC (Alpha), B.1.351 VOC (Beta) and B.1.617.2 (Delta).
