Potent neutralization of clinical isolates of SARS-CoV-2 D614 and G614 variants by a monomeric, sub-nanomolar affinity nanobody
Guillermo Valenzuela Nieto, Ronald Jara, Daniel Watterson, Naphak Modhiran, Alberto A. Amarilla, Johanna Himelreichs, Alexander A. Khromykh, Constanza Salinas-Rebolledo, Teresa Pinto, Yorka Cheuquemilla, Yago Margolles, Natalia López‐González del Rey, Zaray Miranda-Chacón, Alexei Cuevas, Anne Berking, Camila Deride, Sebastián González-Moraga, Héctor Mancilla, Daniel Maturana, Andreas Langer, Juan Pablo Toledo, Ananda Müller, Benjamín Uberti, Paola Krall, Pamela Ehrenfeld, Javier Blesa, Pedro Chaná‐Cuevas, Germán Rehren, David Schwefel, Luis Ángel Fernández, Alejandro Rojas‐Fernández
Abstract
Despite unprecedented global efforts to rapidly develop SARS-CoV-2 treatments, in order to reduce the burden placed on health systems, the situation remains critical. Effective diagnosis, treatment, and prophylactic measures are urgently required to meet global demand: recombinant antibodies fulfill these requirements and have marked clinical potential. Here, we describe the fast-tracked development of an alpaca Nanobody specific for the receptor-binding-domain (RBD) of the SARS-CoV-2 Spike protein with potential therapeutic applicability. We present a rapid method for nanobody isolation that includes an optimized immunization regimen coupled with VHH library E. coli surface display, which allows single-step selection of Nanobodies using a simple density gradient centrifugation of the bacterial library. The selected single and monomeric Nanobody, W25, binds to the SARS-CoV-2 S RBD with sub-nanomolar affinity and efficiently competes with ACE-2 receptor binding. Furthermore, W25 potently neutralizes SARS-CoV-2 wild type and the D614G variant with IC50 values in the nanomolar range, demonstrating its potential as antiviral agent.