Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant antigens (Omicron antigens)

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Omicron variant antigens primarily comprise the structural proteins of the B.1.1.529 lineage, most notably the heavily mutated Spike (S) glycoprotein. The Spike protein is essential for viral pathogenesis as it facilitates host cell attachment by binding to the human angiotensin-converting enzyme 2 (ACE2) receptor and mediates subsequent membrane fusion. The Omicron variant is distinguished by an unprecedented number of mutations, including over 30 amino acid substitutions in the Spike protein, with many occurring in the critical receptor-binding domain (RBD). These alterations significantly enhance viral binding affinity and facilitate immune evasion by reducing the neutralization potency of antibodies generated from prior infections or ancestral-strain vaccines. Consequently, the Omicron antigens represent a critical target for drug development, necessitating the design of broadly neutralizing monoclonal antibodies and updated bivalent vaccine formulations to maintain therapeutic efficacy against evolving sublineages.

Other names

SARS-CoV-2 B.1.1.529 antigensOmicron variant Spike proteinSARS-CoV-2 Omicron variant S proteinLineage B.1.1.529 structural proteins

Monoclonal antibodies and entry inhibitors bind to specific epitopes on the Spike protein, such as the receptor-binding domain (RBD) or N-terminal domain (NTD), to sterically hinder the interaction with the host ACE2 receptor or prevent the conformational changes required for viral-host membrane fusion.