CloneID: aRBD-2
Antigen Long Description: The original antibody was generated by immunizing two alpacas with highly purified recombinant SARS-CoV-2 RBD, and developing a VHH library. The antibody was isolated by panning against SARS-CoV-2 RBD.
Buffer Composition: PBS only.
Uniprot Accession No.: P0DTC2
Specificity Statement: The antibody binds the Spike protein of the SARS-CoV-2.
Application Notes (Clone): The VHH and VHH with IgG1 Fc formats demonstrated strong binding to both RBD and the entire ectodomain (S1+S2) of SARS-CoV-2 spike in ELISA, with a low nanomolar 50% effective concentration (EC50 respectively 1.338 nM and 1.521 nM). The binding affinity of the VHH format and VHH-Fc formats to RBD were also measured using surface plasmon resonance, with KD values of 2.60 nM and 1.57 nM respectively. Both VHH and Fc fusion formats could block RBD-ACE2 interaction in a dose-dependent manner, as characterized by competitive ELISA. Furthermore, the fusion of two VHHs with nonoverlapping epitopes resulted in two hetero-bivalent VHHs, aRBD-2-5 and aRBD-2-7, showed significantly higher RBD binding affinities (KD of 59.2 pM and 0.25 nM). Similarly, their Fc fusions also showed enhanced binding affinities, with KD values of 12.3 pM and 0.22 nM, respectively. The homo- and hetero-bivalent VHHs exhibited potent neutralizing ability against SARSCoV-2 inoculated onto Vero E6 cells. The 50% neutralization doses were 0.092mg/ml (1.12 nM) for aRBD-2-Fc, 1.22 ng/ml (0.043 nM) for aRBD-2-5 and 3.18 ng/ml (0.111 nM) for aRBD-2-7. Finally, the ND50s for aRBD-2-5-Fc and aRBD-2-7-Fc were 11.8 ng/ml (0.107 nM) and 6.76 ng/ml (0.0606 nM), respectively (Ma et al, 2021; PMID:33658349).
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