Severe acute respiratory syndrome coronavirus 2 Omicron XBB.1.5 spike protein (SARS-CoV-2 XBB.1.5 S protein) (SARS-CoV-2 XBB.1.5 S protein)

The SARS-CoV-2 Omicron XBB.1.5 spike protein is the primary surface glycoprotein of the XBB.1.5 subvariant, a recombinant lineage of the Omicron variant (WHO, 2023). It plays a critical role in viral pathogenesis by mediating attachment to the host cell via the Angiotensin-converting enzyme 2 (ACE2) receptor and subsequent membrane fusion (Nature, 2023). XBB.1.5 is characterized by specific mutations, notably F486P, which significantly enhance its binding affinity to ACE2 compared to previous subvariants while maintaining high levels of immune evasion (Cell Host & Microbe, 2023). This protein is the central target for the 2023-2024 updated monovalent mRNA and protein-based vaccines, such as those from Pfizer-BioNTech and Moderna, designed to elicit neutralizing antibodies (FDA, 2023). Due to its rapid evolution, many previously authorized monoclonal antibodies have lost clinical efficacy against this specific spike conformation (The Lancet Infectious Diseases, 2023). Understanding its structural changes is vital for developing next-generation therapeutics and monitoring the trajectory of the COVID-19 pandemic.

Other names

XBB.1.5 spike proteinOmicron XBB.1.5 S proteinKraken variant spike proteinSARS-CoV-2 XBB.1.5 spike

Neutralization of viral entry by blocking the interaction between the spike protein's receptor-binding domain (RBD) and the host Angiotensin-converting enzyme 2 (ACE2) receptor (PubMed, 2023).