SARS-CoV-2 spike protein receptor-binding domain Class 1 epitope (SARS-CoV-2 RBD Class 1 epitope)

The SARS-CoV-2 spike protein receptor-binding domain (RBD) Class 1 epitope is a highly potent neutralizing site located on the 'up' conformation of the spike protein's RBD (Barnes et al., 2020, Nature). This epitope directly overlaps with the binding interface of the human Angiotensin-Converting Enzyme 2 (ACE2) receptor, which the virus uses to enter host cells (UniProt P0DTC2). Antibodies targeting this specific site, such as those derived from the IGHV3-53 or IGHV3-66 germlines, function by physically blocking the RBD from docking with ACE2 (Yuan et al., 2020, Science). Because this region is critical for viral fitness and entry, it has been a primary focus for the development of therapeutic monoclonal antibodies like Casirivimab and Etesevimab (FDA, 2021). However, the Class 1 epitope is particularly susceptible to mutations, such as the N501Y and K417N substitutions found in several variants, which can alter antibody binding affinity and lead to immune evasion (Harvey et al., 2021, Nature Reviews Microbiology). Understanding the structural landscape of this epitope is essential for designing next-generation vaccines and therapeutics that can withstand viral evolution.

Other names

Class 1 RBD epitopeRBD Class 1 siteACE2-binding site epitope (Class 1)IGHV3-53/3-66-encoded epitope

Neutralization of viral infection by sterically blocking the interaction between the viral receptor-binding domain (RBD) and the host Angiotensin-Converting Enzyme 2 (ACE2) receptor (Barnes et al., 2020, Nature).