Engineered Multivalent Nanobodies Potently and Broadly Neutralize SARS‐CoV‐2 Variants

The COVID‐19 pandemic continues to be a severe threat to human health, especially due to current and emerging SARS‐CoV‐2 variants with potential to escape humoral immunity developed after vaccination or infection. The development of broadly neutralizing antibodies that engage evolutionarily conserved epitopes on coronavirus spike proteins represents a promising strategy to improve therapy and prophylaxis against SARS‐CoV‐2 and variants thereof. Herein, a facile multivalent engineering approach is employed to achieve large synergistic improvements in the neutralizing activity of a SARS‐CoV‐2 cross‐reactive nanobody (VHH‐72) initially generated against SARS‐CoV. This synergy is epitope specific and is not observed for a second high‐affinity nanobody against a non‐conserved epitope in the receptor‐binding domain. Importantly, a hexavalent VHH‐72 nanobody retains binding to spike proteins from multiple highly transmissible SARS‐CoV‐2 variants (B.1.1.7 and B.1.351) and potently neutralizes them. Multivalent VHH‐72 nanobodies also display drug‐like biophysical properties, including high stability, high solubility, and low levels of non‐specific binding. The unique neutralizing and biophysical properties of VHH‐72 multivalent nanobodies make them attractive as therapeutics against SARS‐CoV‐2 variants.This work reports a multivalent engineering strategy to synergistically increase the neutralization potency of nanobodies against SARS‐CoV‐2. An engineered hexavalent nanobody directed against an evolutionarily conserved epitope potently neutralizes SARS‐CoV‐2 and two key variants of concern (B.1.1.7 and B.1.351). This facile approach significantly improves the neutralization breadth and potency of promising nanobodies for potential use in therapeutic applications.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/169325/1/adtp202100099_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/169325/2/adtp202100099.pd