Abstract
BackgroundThe outbreak and pandemic of coronavirus SARS-CoV-2 caused significant threaten to global public health and economic consequences. It is extremely urgent that global people must take actions to develop safe and effective preventions and therapeutics. Nanobodies, which are derived from single‑chain camelid antibodies, had shown antiviral properties in various challenge viruses. In this study, multivalent nanobodies with high affinity blocking SARS-CoV-2 spike interaction with ACE2 protein were developed.ResultsTotally, four specific nanobodies against spike protein and its RBD domain were screened from a naïve VHH library. Among them, Nb91-hFc and Nb3-hFc demonstrated antiviral activity by neutralizing spike pseudotyped viruses in vitro. Subsequently, multivalent nanobodies were constructed to improve the neutralizing capacity. As a result, heterodimer nanobody Nb91-Nb3-hFc exhibited the strongest RBD-binding affinity and neutralizing ability against SARS-CoV-2 pseudoviruses with an IC50 value at approximately 1.54 nM.ConclusionsThe present study indicated that naïve VHH library could be used as a potential resource for rapid acquisition and exploitation of antiviral nanobodies. Heterodimer nanobody Nb91-Nb3-hFc may serve as a potential therapeutic agent for the treatment of COVID-19.
Highlights
The outbreak and pandemic of coronavirus SARS-CoV-2 caused significant threaten to global public health and economic consequences
Construction of the naïve VHH library Total 4.3 × 108 peripheral blood lymphocytes (PBLs) were isolated from 200 mL Bactrian camel blood samples
The results showed that recombinant receptor-binding domain (RBD) proteins (27 kDa) were expressed successfully and the target was obtained after purification (Fig. 1b), there were several bands in the S protein lane (Fig. 1b), and the possible reason is that S protein was cleaved at the S1/S2 protease cleavage site, in keeping with published data [34,35,36]
Summary
The outbreak and pandemic of coronavirus SARS-CoV-2 caused significant threaten to global public health and economic consequences. Multivalent nanobodies with high affinity blocking SARS-CoV-2 spike interaction with ACE2 protein were developed. Coronavirus disease 2019 (COVID-19) is caused by infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) [1, 2]. It has spread global and had been announced by World Health Organization (WHO) in March 2020 as the first coronavirus severe pandemic in the history of humanity [3, 4]. SARS-CoV-2 is an enveloped virus that belongs to the family Coronaviridae, the subfamily Orthocoronaviridae and genus β-coronavirus [5]. Its genome consists of six functional open-reading frames (ORFs), which encoded replicase (ORF1a/ORF1b), membrane (M), spike glycoprotein (S), envelope (E) and
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