SARS-CoV-2 spike protein receptor-binding domain (Delta, BA.5, and XBB.1.5 variants) (SARS-CoV-2 S-RBD)

The SARS-CoV-2 spike protein receptor-binding domain (RBD) is a critical component of the S1 subunit of the viral spike glycoprotein. Its primary biological function is to mediate the high-affinity attachment of the virus to the host cell's angiotensin-converting enzyme 2 (ACE2) receptor, which is the essential first step for viral entry and subsequent infection [1, 7, 14]. Mutations within the RBD, such as those found in the Delta (L452R, T478K), BA.5 (L452R, F486V), and XBB.1.5 (F486P) variants, significantly influence the virus's transmissibility and its ability to evade host immune responses [1, 8, 12]. These variants have progressively evolved to increase ACE2 binding affinity or to escape neutralization by antibodies elicited by previous infections or vaccinations [1, 8]. Consequently, the RBD is the primary target for both prophylactic vaccines and therapeutic monoclonal antibodies [2, 9, 15]. While early monoclonal antibodies like bebtelovimab and the tixagevimab/cilgavimab combination lost efficacy against newer Omicron subvariants, updated treatments such as pemivibart and XBB.1.5-specific monovalent vaccines have been developed to address these specific antigenic changes [3, 9, 12].

Other names

Spike RBDS-RBDSARS-CoV-2 S protein RBDReceptor-binding domain of the SARS-CoV-2 spike protein

Neutralization of viral entry by competitively inhibiting the interaction between the viral receptor-binding domain and the host cell angiotensin-converting enzyme 2 (ACE2) receptor.