The Spike (S) protein is a type I transmembrane glycoprotein present on the surface of coronaviruses (CoV). Entry of CoV into host cells is mediated by the S protein, where it interacts with the cell-surface receptor angiotensin-converting enzyme 2 (ACE2). In humans, ACE2 is expressed in several organs and tissues, including intestinal and respiratory epithelium.
The S protein has two subunits, S1 and S2, where S1 primarily consists of the 193 amino acid long RBD and the N-terminal domain (NTD). The S2 domain is responsible for membrane fusion. During CoV infection, the S protein is cleaved into the N-terminal S1 subunit and C-terminal S2 subunit by host proteases, transforming its conformation from the pre-fusion to the post-fusion state. The S protein has been shown to play a key role in the induction of neutralizing antibody and T cell responses, which may lead to protective immunity. The RBD binds to ACE2, while the function of the NTD is not well understood. The Covi-2 antibody blocks the interaction of the S1 subunit with the ACE2 receptor and binds to a different epitope than the Covi-1 antibody.
Data and Publications
Figure 1. Inhibitory Effect of Covi-2 Antibody on Spike Protein Receptor-Binding Domain and ACE2 Interaction
ELISA binding assay shows that at high concentrations, Anti-SARS-CoV-2 Spike Protein S1 Receptor-Binding Domain Antibody, Clone Covi-2 (Blocking/Recombinant) (orange line) blocks biotinylated recombinant human ACE2 from binding to an ELISA plate coated with recombinant SARS-CoV-2 Spike protein S1 RBD, in comparison to a negative control antibody (blue line). The binding of biotinylated recombinant human ACE2 to the Spike protein S1 RBD was detected using streptavidin horseradish peroxidase (HRP). The results were plotted as (A) absorbance (450 nm) or (B) binding percentage.