Figure 1.

Identification of neutralizing antibodies with a PtY display platform. We first used our preconstructed naïve phage displayed human scFv library to screen binders with biotinylated SARS-CoV-2 RBD protein in the solution phase. After enrichment of phage binders, the scFv DNA from enriched binders was cloned into the yeast display plasmid, resulting in display of scFv on the yeast cell surface. We then performed FACS to isolate potential blocking antibodies that could prevent binding of the SARS-CoV-2 RBD to hACE2. The 0.013% gate contained blocking antibodies with high affinity toward RBD. That is, higher Y axis signal represented higher affinity to labeled RBD, whereas lower X signal represented higher potency in blocking the binding of differently labeled hACE2 to RBD. The potential blocking antibodies were sent for sequencing and transient expression. The purified antibodies were evaluated for affinity, blocking activity, biophysical properties, and virus-neutralizing activity