Fig. 1: Induction of shark IgNAR antibody responses and isolation of antigen-specific VNARs.

a Immunization schedule of six nurse sharks for VNAR isolation. Sharks “Pink” and “Red” were immunized with SARS-CoV-2 RBD protein, followed by panning and identification of ShAb01 and ShAb02. Nurse sharks ‘Green’ and ‘Yellow’ were immunized with SARS-CoV-2 RBD-ferritin nanoparticle, followed by panning and identification of ShAb17-18 & 21 VNAR molecules. Nurse sharks ‘Purple’ and ‘Blue’ were immunized with SARS-CoV-2 Spike-ferritin nanoparticle, followed by panning and identification of ShAb09 and ShAb22-25 & 27–29 VNAR molecules. b Shark IgNAR peak plasma titers from all animals tested against SARS-CoV-2 RBD by ELISA. Pre-bleed samples serve as the negative control for each animal. c Shark IgNAR peak plasma titers from SpFN immunized animals (‘Purple’ and ‘Blue’) tested against SARS-CoV-2 S-2P by ELISA. Pre-bleed samples serve as the negative control for each animal. d Flow-chart depicting the steps involved from initial shark peripheral blood lymphocyte (PBL) isolation to ShAb protein expression. e ELISA of ShAb-Fc molecules against SARS-CoV-2 RBD (top) and S-2P trimer (bottom). Background binding to blocking agent, bovine serum albumin, has been subtracted from each data point. Source data are provided as a Source Data file. The shark image was created with BioRender.com.