$SRNE Affinity engineering ...The nAb candidate termed STI-1499 displayed potent SARS-CoV-2 neutralizing activity superior to that of other G-MAB nAb hits, with an IC50 in the virus neutralization assay of 3.2 μg/ml. In parallel to STI-1499 preclinical profiling and cell line development efforts, affinity maturation of STI-1499 was undertaken, with systematic amino acid changes engineered within complementarity determination regions (CDRs) of the STI-1499 heavy and light chains. For individual CDR regions from STI-1499, a library of variants was screened for binding to the Spike S1 subunit by ELISA. Variants bearing combinations of affinity-enhancing CDR amino acid changes were then systematically engineered and expressed as IgG1 LALA antibodies. Based on Spike S1 ELISA binding results, the most potent clone of the single CDR and combination CDR variants, STI-2020, was further profiled for binding affinity using surface plasmon resonance (SPR). ...
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