Severe acute respiratory syndrome coronavirus 2 spike glycoprotein Omicron BA.1 variant (SARS-CoV-2 S (Omicron BA.1))

The SARS-CoV-2 spike protein Omicron BA.1 variant is a heavily mutated version of the viral surface glycoprotein that mediates entry into human host cells. It contains over 30 mutations in the spike gene, with approximately 15 located in the critical receptor-binding domain (RBD), which significantly enhances its affinity for the human angiotensin-converting enzyme 2 (ACE2) receptor while simultaneously facilitating escape from neutralizing antibodies [1, 13, 15]. Unlike previous variants, Omicron BA.1 shows a preference for the endosomal entry pathway and reduced dependence on the host protease TMPRSS2, contributing to its altered tissue tropism and high transmissibility [2, 4]. As a primary therapeutic target, this protein is the focus of monoclonal antibody treatments and the antigenic component of most COVID-19 vaccines. However, the extensive mutations in BA.1 led to the loss of neutralizing activity for several early-pandemic monoclonal antibodies, such as the Casirivimab/Imdevimab cocktail, while others like Bebtelovimab retained efficacy [7, 12]. The protein's role in disease is central to the global spread of the Omicron variant, necessitating the development of bivalent vaccine boosters designed to recognize these specific structural changes [7, 14]. Understanding the structural dynamics of this variant remains vital for monitoring viral evolution and ensuring the continued efficacy of COVID-19 countermeasures [15, 16].

Other names

B.1.1.529.1 spike proteinOmicron BA.1 spikeSARS-CoV-2 S protein (BA.1)21K (Nextstrain clade)Spike glycoprotein Omicron variant

Neutralization of viral particles by blocking the receptor-binding domain (RBD) interaction with human ACE2; inhibition of viral-host membrane fusion; induction of protective humoral and cellular immune responses through vaccination.