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

The Class 2 epitope of the SARS-CoV-2 spike protein receptor-binding domain (RBD) is a critical antigenic site targeted by potent neutralizing antibodies (Barnes et al., 2020). This epitope is characterized by its accessibility in both the "up" and "down" conformations of the RBD and its significant overlap with the Angiotensin-Converting Enzyme 2 (ACE2) binding motif (Starr et al., 2021). Therapeutic monoclonal antibodies, such as Bamlanivimab and Regdanvimab, bind to this site to sterically block the virus from attaching to host cells (NIH, 2021). However, the Class 2 epitope is a hotspot for mutations, most notably the E484K substitution, which can lead to substantial immune evasion and reduced drug efficacy (Greaney et al., 2021). Consequently, while it remains a primary focus for therapeutic development, the high mutability of this region necessitates continuous monitoring of viral variants and often requires the use of combination antibody cocktails to maintain clinical effectiveness (CDC, 2022).

Other names

RBD Class 2 siteClass 2 neutralizing epitopeACE2-binding motif (RBM) Class 2 epitopeE484-containing epitope

Neutralization of viral entry by sterically hindering the interaction between the viral receptor-binding domain (RBD) and the host Angiotensin-Converting Enzyme 2 (ACE2) receptor (Barnes et al., 2020; NIH, 2021).