Neutralizing antibodies are of particular interest to scientists. They efficiently stop the infection by blocking the interaction between the SARS-CoV-2 virus and the host cells. Most neutralizing antibodies respond to the receptor binding domain (RBD) of the spike protein, which binds directly to the cell surface receptor ACE2. antibodies-online currently offers two neutralizing antibodies based on the clone CR3022. While most S-protein RBD binding antibodies compete for antigen binding with ACE2, the CR3022 epitope does not overlap with the ACE2-binding site. It does thus not hinder binding of neutralizing antibodies. While CR3022 on its own exhibits only a weak neutralizing effect, it has been shown to synergize with other S-protein RBD binding antibodies to neutralize SARS-CoV. This effect still has to be confirmed in context with SARS-CoV-2.3
Available SARS-CoV-2 Neutralizing Antibodies based on Clone CR3022
A part of antibodies produced during an immune response are neutralizing antibodies (NAbs). NAbs can inhibit the infectivity binding specifically to surface structures, thus preventing the interaction with its host cells. NAbs are used for passive immunization and also play a role in active immunization by vaccination.
The antibody clone CR3022 (ABIN6952546), which is the basis for both antibodies, was originally isolated from a convalescent SARS patient from Singapore1. The clone was demonstrated to be effective in neutralization assays for different SARS-CoV strains in synergy with other RBD-targeting antibodies. Its epitope does not overlap with the angiotensin-converting enzyme 2 (ACE2) binding site, thus leaving it accessible for other neutralizing antibodies. Since the outbreak of COVID-19, CR3022 has been demonstrated to bind the SARS-CoV-2 S protein RBD in a similar fashion2. Crystallization assays of CR3022 bound to its SARS-CoV-2 target have provided important insights into possible attack points for therapeutics against this virus3. Moreover, CR3022 has been used as a positive control in serological assays to detect antibodies in human serum that bind SARS-CoV-2 S-protein4.
In a recent Nature article SARS-CoV N-Protein Antibody (ABIN6952544) was used by Thao et al. as they established a technique to engineer and resurrect chemically-synthetized clones of the recent epidemic SARS-CoV-2 in only a week after receipt of the synthetic DNA fragments. The technique enables the generation and functional characterization of evolving RNA virus variants—in real-time—during an outbreak.5
They utilized yeast-based TAR cloning to generate viral cDNA clones and virus recovery by transfection. Cell culture supernatants containing viruses produced after virus rescue were electroporated and co-cultivated with susceptible VeroE6 cells. For characterisation of recombinant and synthetic SARS-CoV-2(-GFP) an immunofluorescence assay was perfomed. 48 hours after infection, cells were fixed and prepared for immunofluorescence staining with primary antibodies directed against double-stranded RNA (dsRNA) and SARS-CoV-2 N protein antibody (ABIN6952544) to visualize GFP expression.