SARS-CoV-2 spike protein XBB.1.5 (S protein (XBB.1.5))

The SARS-CoV-2 spike protein XBB.1.5 is a critical surface glycoprotein of the Omicron XBB.1.5 subvariant, which emerged as a dominant lineage of the virus responsible for COVID-19 [1, 11]. As a Class I fusion protein, it facilitates viral entry into host cells by specifically binding to the human Angiotensin-Converting Enzyme 2 (ACE2) receptor [1, 9, 12]. This variant is distinguished by a unique set of mutations, including the S486P substitution in the receptor-binding domain, which markedly increases its affinity for ACE2 and enhances its transmissibility [1, 11]. The protein serves as the primary antigen for updated monovalent vaccines, such as those developed by Pfizer-BioNTech, Moderna, and Novavax, which are designed to stimulate the production of neutralizing antibodies [4, 6, 19]. These vaccines aim to block the interaction between the spike protein and the host receptor, thereby preventing infection and reducing disease severity [5, 12]. However, the protein's high rate of mutation and capacity for immune evasion present ongoing challenges for therapeutic development and long-term vaccine effectiveness [1, 5, 11]. Monitoring the evolution of this target is essential for the design of next-generation boosters and monoclonal antibody treatments [1, 14].

Other names

Omicron XBB.1.5 spike proteinSARS-CoV-2 S protein (XBB.1.5)XBB.1.5 S proteinSARS-CoV-2 spike glycoprotein (XBB.1.5)

Neutralization of viral entry by blocking the interaction between the viral spike protein and the host ACE2 receptor, thereby preventing membrane fusion and infection [1, 9, 12].