Prama Ghosh, Amity University Kolkata
The alarming hypothesis that the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic to be around for several years calls for rapid and successful therapies. Though anti-SARS-CoV-2 spike monoclonal antibodies originated from mice have shown robust performance in various immunoassays including western blotting, ELISA, immunofluorescence, and immunoprecipitation, there is still a lack of data for studying the life cycle of the virus.
In light of this need, scientists have established six monoclonal antibodies against the spike glycoprotein of SARS-CoV-2 and reported the in vitro attenuation of viral interaction with cells. The SARS-CoV-2 spike glycoprotein is a homotrimeric fusion protein Composed of two subunits: S1 and S2, the SARS-CoV-2 spike glycoprotein is a homotrimeric fusion protein.
A stable homotrimer, resistant to proteolysis during protein preparation, was formed by engineering SARS-CoV-2 spike protein according to the methodology of Wrapp et al., 2020. These recombinant spike proteins were then injected to mice to generate anti – SARS-CoV-2 antibodies. The culture supernatants showed the presence of six monoclonal antibodies which were purified and characterized.
Antibodies S1D7 and S3D8 showed higher performance on IP (immunoprecipitation) and IF (immunofluorescence)
The clones of these antibodies were capable of immunoprecipitation (IP) with the RBD and ectodomain (S∆TM) glycoproteins with a differential IP efficiency. The cellular localization of spike proteins was reflected by immunofluorescence assay, which elucidated the mechanism of packaging and maturation of variance during release from the cellular membrane.
ACE2-Spike binding inhibition of the monoclonal antibodies
The competitive binding between neutralizing antibodies and spike glycoprotein intercepts spike-ACE2 interaction thus, neutralizing SARS-CoV-2 infection.
S1D7 and S3D8 showed neutralizing activity against SARS-CoV-2
VeroE6/TM2 cells are more prone to virus infection than VeroE6 cell line which is commonly adopted. When these two antibodies were mixed, immediate neutralizing activity was observed thereby showing an inhibitory mechanism.
The mouse antibodies can be used for investigating the mechanism of immune responses for SARS-CoV-2 infection but they do not apply for clinical uses1.
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