Shark nanobodies with potent SARS-CoV-2 neutralizing activity and broad sarbecovirus reactivity

Despite rapid and ongoing vaccine and therapeutic development, SARS-CoV-2 continues to evolve and evade, presenting a need for next-generation diverse therapeutic modalities. Here we show that nurse sharks immunized with SARS-CoV-2 recombinant receptor binding domain (RBD), RBD-ferritin (RFN), or spike protein ferritin nanoparticle (SpFN) immunogens elicit a set of new antigen receptor antibody (IgNAR) molecules that target two non-overlapping conserved epitopes on the spike RBD. Representative shark antibody variable NAR-Fc chimeras (ShAbs) targeting either of the two epitopes mediate cell-effector functions, with high affinity to all SARS-CoV-2 viral variants of concern, including the divergent Omicron strains. The ShAbs potently cross-neutralize SARS-CoV-2 WA-1, Alpha, Beta, Delta, Omicron BA.1 and BA.5, and SARS-CoV-1 pseudoviruses, and confer protection against SARS-CoV-2 challenge in the K18-hACE2 transgenic mouse model. Structural definition of the RBD-ShAb01-ShAb02 complex enabled design and production of multi-specific nanobodies with enhanced neutralization capacity, and picomolar affinity to divergent sarbecovirus clade 1a, 1b and 2 RBD molecules. These shark nanobodies represent potent immunotherapeutics both for current use, and future sarbecovirus pandemic preparation.

Wei-Hung Chen, Agnes Hajduczki, Elizabeth J Martinez, Hongjun Bai, Hanover Matz, Thomas M Hill, Eric Lewitus, William C Chang, Layla Dawit, Caroline E Peterson, Phyllis A Rees, Adelola B Ajayi, Emily S Golub, Isabella Swafford, Vincent Dussupt, Sapna David, Sandra V Mayer, Sandrine Soman, Caitlin Kuklis, Courtney Corbitt, Jocelyn King, Misook Choe, Rajeshwer S Sankhala, Paul V Thomas, Michelle Zemil, Lindsay Wieczorek, Tricia Hart, Debora Duso, Larry Kummer, Lianying Yan, Spencer L Sterling, Eric D Laing, Christopher C Broder, Jazmean K Williams, Edgar Davidson, Benjamin J Doranz, Shelly J Krebs, Victoria R Polonis, Dominic Paquin-Proulx, Morgane Rolland, William W Reiley, Gregory D Gromowski, Kayvon Modjarrad, Helen Dooley, M Gordon Joyce