SARS-CoV-2 Variants (Omicron) S RBD

The spike (S) glycoprotein is essential for both host specificity and viral infectivity. SARS-CoV-2 can infect the human respiratory epithelial cells through interaction with the human ACE2 receptor. The SARS-CoV-2 B.1.1.529 variant was first reported to WHO from South Africa on 24 November 2021. WHO has designated B.1.1.529 as a VOC, named Omicron. The spike protein is a large type I transmembrane protein containing two subunits, S1 and S2. S1 mainly contains a receptor binding domain (RBD), which is responsible for recognizing the cell surface receptor. S2 contains basic elements needed for the membrane fusion. The S protein plays key parts in the induction of neutralizing-antibody and T-cell responses, as well as protective immunity.