Severe acute respiratory syndrome coronavirus 2 spike glycoprotein (S protein)

The Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike glycoprotein is a large, trimeric class I fusion protein that decorates the exterior of the virus, facilitating its entry into host cells (UniProt P0DTC2). It consists of two primary subunits: S1, which contains the receptor-binding domain (RBD) that attaches to the human angiotensin-converting enzyme 2 (ACE2) receptor, and S2, which mediates the fusion of the viral and cellular membranes (Wikipedia). As the most prominent surface antigen, the spike protein is the primary target for the majority of COVID-19 vaccines and monoclonal antibody therapies (NIH). These medical interventions aim to generate or provide neutralizing antibodies that disrupt the spike-ACE2 interaction, effectively blocking infection. However, the protein is subject to significant mutational pressure, leading to the emergence of variants of concern that can exhibit increased transmissibility or partial escape from existing immunity (NIH). Beyond its role in viral entry, the spike protein has been shown to induce inflammatory responses and direct vascular endothelial damage, contributing to the multi-organ complications observed in COVID-19 (Salk Institute). Therapeutic strategies also include fusion inhibitors that target the conserved regions of the S2 subunit to prevent viral entry across different variants (NIH). Monitoring of anti-spike antibody levels and neutralizing titers serves as a key biomarker for assessing vaccine efficacy and population immunity (NIH).

Other names

Spike glycoproteinS glycoproteinE2Peplomer proteinSARS-CoV-2 S proteinSpike protein S1Spike protein S2

Vaccines induce active immunity by presenting the spike protein or its genetic code to the immune system, leading to the production of neutralizing antibodies and T-cell responses (Mayo Clinic). Monoclonal antibodies bind to specific epitopes on the spike protein, such as the receptor-binding domain (RBD), to competitively inhibit binding to the host ACE2 receptor and prevent viral entry (NIH). Fusion inhibitors target the S2 subunit to block the conformational changes required for viral-host membrane fusion (NIH).