Spike glycoprotein of SARS-CoV-2 XBB.1.5 (S protein (S glycoprotein))

The spike glycoprotein of SARS-CoV-2 XBB.1.5 is a trimeric, surface-exposed transmembrane protein that decorates the viral envelope and mediates entry into human cells by binding the ACE2 receptor. It comprises two subunits: S1 (containing the receptor-binding domain, RBD) and S2 (containing the fusion peptide and heptad repeats for membrane fusion). The XBB.1.5 variant features several amino acid mutations (notably S486P in the RBD) that enhance its ability to bind ACE2 and confer increased immune escape against therapeutic antibodies, while maintaining similar overall spike architecture to prior Omicron sublineages[1][3][4][5]. The spike protein is the principal antibody and vaccine target, but rapid evolution generates new antigenic variants, complicating immunotherapeutic strategies.

Other names

Spike protein of SARS-CoV-2 XBB.1.5S protein (S glycoprotein) of XBB.1.5SARS-CoV-2 S protein XBB.1.5 variantOmicron XBB.1.5 spike

Antibodies: Neutralization via direct binding to the spike RBD or other immunodominant regions, blocking ACE2 interaction Vaccines: Induction of immune responses primarily via generation of anti-spike antibodies Small molecules: Inhibition of spike-ACE2 interaction or protease-mediated spike activation