SARS-CoV-2 spike protein receptor-binding domain, Omicron XBB.1.5 subvariant (XBB.1.5 RBD)

The SARS-CoV-2 spike protein receptor-binding domain (RBD) of the Omicron XBB.1.5 subvariant is a critical component of the viral envelope that mediates host cell entry. XBB.1.5, a recombinant sublineage of Omicron, features a key F486P mutation in the RBD that significantly enhances its binding affinity for the human angiotensin-converting enzyme 2 (ACE2) receptor compared to its predecessors [1, 5]. This increased affinity, combined with extensive mutations that facilitate evasion of neutralizing antibodies, contributed to its rapid global spread and dominance in early 2023 [8, 15]. The RBD serves as the primary target for neutralizing antibodies elicited by both natural infection and vaccination [4, 23]. Due to the significant antigenic shift in XBB.1.5, many previously authorized monoclonal antibodies, such as Bebtelovimab and the Evusheld combination, lost their clinical efficacy [13, 14]. This necessitated the development of updated monovalent vaccines from manufacturers like Pfizer-BioNTech, Moderna, and Novavax, which specifically target the XBB.1.5 spike protein to restore protective immunity [20, 22]. Understanding the structural dynamics of this domain remains vital for monitoring viral evolution and developing next-generation therapeutics [10].

Other names

KrakenXBB.1.5 RBDSARS-CoV-2 Omicron XBB.1.5 Spike RBDXBB.1.5 S-RBDSARS-CoV-2 S-protein RBD (XBB.1.5)

Neutralization of viral entry by blocking the interaction between the viral receptor-binding domain (RBD) and the host cell angiotensin-converting enzyme 2 (ACE2) receptor [1, 21].