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 therapeutic potential 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 high-affinity 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.
Competing Interest Statement
Conflict of interest statement The Austral University of Chile claiming priority to U.S. Provisional Patent Application No. US Serial No. 63/025534, filed MAY-2020.
Footnotes
Developing a rapid method for nanobody isolation which allows single-step selection of high-affinity nanobodies, by using a simple density gradient centrifugation of the bacterial library, allowed us to identify a very high affinity nanobody against the Spike protein of SARS-CoV-2 which we called W25. We determined that W25 binds to the SARS-CoV-2 Spike RBD with sub-nanomolar affinity and efficiently competes with ACE-2 receptor binding. Furthermore, the W25 nanobody potently neutralizes SARS-CoV-2 wild type and the D614G variant with IC50 values in the nanomolar range, demonstrating its potential as an antiviral agent.
