SARS-CoV-2 Omicron XBB.1.5 spike glycoprotein receptor-binding domain (S-RBD) (SARS-CoV-2 XBB.1.5 S-RBD)

The SARS-CoV-2 Omicron XBB.1.5 spike glycoprotein receptor-binding domain (RBD) is a primary target for neutralizing antibodies and a critical mediator of viral entry into human cells. As a component of the S1 subunit, the RBD binds to the host's angiotensin-converting enzyme 2 (ACE2) receptor, a process facilitated by the protein's transition from a closed to an open conformational state [4, 12]. The XBB.1.5 subvariant, a recombinant of BA.2 lineages, contains specific mutations like F486P that enhance its ACE2 binding affinity and contribute to its high transmissibility and immune evasion [8, 11]. The M39 antibody is a human monoclonal antibody that recognizes a specific epitope on this RBD, forming hydrogen bonds with residues N439, K440, and Q506 [1]. By targeting this footprint, M39 effectively neutralizes XBB.1.5 and related strains such as JN.1, preventing the virus from attaching to and infecting host cells [3, 7]. This epitope represents a significant site for therapeutic intervention, although the rapid evolution of the virus poses a continuous risk of escape mutations that could bypass antibody-mediated protection [6, 15].

Other names

SARS-CoV-2 XBB.1.5 Spike RBDOmicron XBB.1.5 S-protein RBDM39 antibody epitopeKraken variant spike RBD

Neutralization of viral infection by binding to the receptor-binding domain (RBD) of the spike protein, thereby sterically hindering or competitively inhibiting the interaction with the host cell receptor ACE2 [1, 12].