Anti-S protein (RBD) [STE90-C11]

Absolute Antibody

Anti-S protein (RBD) [STE90-C11]

7

The specificity of this antibody (IgG) for RBD, S1 or S1-S2 was confirmed by ELISA analysis, with EC50= 0.2 nM, 0.2 nM and 0.3 nM respectively. Inhibition assay was performed by flow cytometry on ACE-2 expressing EXPI293F cells, measuring direct competition between S1-S2 trimer and the scFv-Fc antibody; the antibody inhibited the S1-S2 binding for more than 90%. Inhibition of ACE2 binding was assessed in a cell-based inhibition assay. The antibody showed half-maximal inhibitory concentration (IC50) values of 2.6 nM IgG for 50 nM S1-S2 Spike and 1 nM IgG for 10 nM RBD. For 50% inhibition, the molar ratios were from 0.05 and 0.03:1 (antibody binding site: antigen). To confirm the neutralizing activity of the antibody, a plaque assay using ~ 150 pfu was performed and the determined IC50 was 0.56 nM in the IgG format. The SARS-CoV-2 neutralizing effect of the antibody was tested in vivo in a Syrian hamster challenge model. The virus titer in the lung of treated animals showed a dose-dependent reduction of viral load on days 3 and 5 after infection. Further, the SARS-CoV-2 neutralizing effect of the antibody was tested in vivo in the transgenic human ACE2 mice model (K18hACE2); in all other mice treated with the antibody, the virus was completely removed from the lungs. Biochemical characterization of the antibody revealed no aggregation under normal conditions (pH 7.4, 45 C, 24 h in PBS), heat stress conditions (pH 7.4, 45C, 24 h in PBS), and pH stress (pH 3, 24 h, room temperature [RT]). The monovalent affinity of the antibody was measured with 1.6-8.1 nM, depending on the bio-layer interferometry setup. The Fab fragment of the antibody was crystallized with the antigen RBD. The antibody derived human IgG1 with FcgammaR-silenced Fc (COR-101) is undergoing to clinical trials for the treatment of COVID-19 (Bertoglio et al, 2021; pmid:34273271).

ELISA, Neutralisation/Blocking, Other Application

ELISA; in vitro inhibition; in vitro neutralization; in vivo protection; crystallography; biolayer interferometry; therapeutic

Research Use Only

Spike glycoprotein

This full-length chimeric mouse antibody was made using the variable domain sequences of the original Human scFv format for improved compatibility with existing reagents assays and techniques.

-20°C,2°C to 8°C

12352203