Fig 1.

Construction and screening of induced nanobody phage display library for anti-SARS-CoV-2 nanobodies. An alpaca was immunized with recombinant prototypic SARS-CoV-2 spike protein and the peripheral blood mononuclear cells were used to construct an induced nanobody phage display library. Panning against the library using the spike protein was performed to identify strong binders, which were then subjected to pseudovirus entry assay for selection of neutralizing nanobodies. Three neutralizing nanobodies (Nanosota-2A, Nanosota-3A, and Nanosota-4A) were discovered, and they all bind to the RBD. Fc-tagged nanobodies were constructed and prepared; their binding kinetics against prototypic SARS-CoV-2 RBD were determined using surface plasmon resonance (SPR). (Alpaca photo courtesy of Tony Hisgett; reprinted with permissionhttps://creativecommons.org/licenses/by/2.0/deed.en.)