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

The **spike glycoprotein of SARS-CoV-2 Omicron XBB.1.5 variant** is a trimeric viral envelope protein responsible for mediating the virus’s entry into host cells by binding to the human ACE2 receptor and promoting membrane fusion[1][4][5][7]. The XBB.1.5 variant spike has evolved specific mutations, such as S486P in its receptor-binding domain (RBD), enhancing its ability to bind ACE2 and increasing its transmissibility and immune evasion relative to previous Omicron and non-Omicron strains[1][5][7]. These mutations remodel major antigenic sites, leading to reduced efficacy of many neutralizing antibodies generated through prior infection, vaccination, or antibody therapy[1][2][7]. The spike glycoprotein is the primary target of most COVID-19 vaccines, including updated boosters which incorporate XBB.1.5 spike sequences to improve protection against emerging Omicron subvariants[3][7]. The spike protein’s ongoing evolution is a central challenge for COVID-19 therapeutic and vaccine strategies, necessitating frequent updates and continuous surveillance.

Other names

Spike protein (S)S proteinSARS-CoV-2 S proteinOmicron XBB.1.5 S proteinOmicron spike protein

Neutralization by antibodies binding to the receptor-binding domain, blocking ACE2 interaction[3][7]; Vaccine-induced immune responses target S protein to elicit neutralizing antibodies and T cell responses[3][7]; Some small molecules aim to inhibit S protein-mediated membrane fusion (experimental)