An ultrapotent synthetic nanobody neutralizes SARS-CoV-2 by stabilizing inactive Spike.
Schoof, M., Faust, B., Saunders, R.A., Sangwan, S., Rezelj, V., Hoppe, N., Boone, M., Billesbolle, C.B., Puchades, C., Azumaya, C.M., Kratochvil, H.T., Zimanyi, M., Deshpande, I., Liang, J., Dickinson, S., Nguyen, H.C., Chio, C.M., Merz, G.E., Thompson, M.C., Diwanji, D., Schaefer, K., Anand, A.A., Dobzinski, N., Zha, B.S., Simoneau, C.R., Leon, K., White, K.M., Chio, U.S., Gupta, M., Jin, M., Li, F., Liu, Y., Zhang, K., Bulkley, D., Sun, M., Smith, A.M., Rizo, A.N., Moss, F., Brilot, A.F., Pourmal, S., Trenker, R., Pospiech, T., Gupta, S., Barsi-Rhyne, B., Belyy, V., Barile-Hill, A.W., Nock, S., Liu, Y., Krogan, N.J., Ralston, C.Y., Swaney, D.L., Garcia-Sastre, A., Ott, M., Vignuzzi, M., Walter, P., Manglik, A.(2020) Science 370: 1473-1479
- PubMed: 33154106 
- DOI: https://doi.org/10.1126/science.abe3255
- Primary Citation of Related Structures:  
7KKJ, 7KKK, 7KKL - PubMed Abstract: 
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus enters host cells via an interaction between its Spike protein and the host cell receptor angiotensin-converting enzyme 2 (ACE2). By screening a yeast surface-displayed library of synthetic nanobody sequences, we developed nanobodies that disrupt the interaction between Spike and ACE2. Cryo-electron microscopy (cryo-EM) revealed that one nanobody, Nb6, binds Spike in a fully inactive conformation with its receptor binding domains locked into their inaccessible down state, incapable of binding ACE2. Affinity maturation and structure-guided design of multivalency yielded a trivalent nanobody, mNb6-tri, with femtomolar affinity for Spike and picomolar neutralization of SARS-CoV-2 infection. mNb6-tri retains function after aerosolization, lyophilization, and heat treatment, which enables aerosol-mediated delivery of this potent neutralizer directly to the airway epithelia.
Organizational Affiliation: 
Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, CA, USA. michael@walterlab.ucsf.edu peter@walterlab.ucsf.edu aashish.manglik@ucsf.edu.