Severe acute respiratory syndrome coronavirus 2 spike protein (SARS-CoV-2 S protein) Omicron BA.5 (SARS-CoV-2 S protein (BA.5))

The SARS-CoV-2 spike protein of the Omicron BA.5 subvariant is a critical viral surface glycoprotein that mediates host cell entry by binding to the human angiotensin-converting enzyme 2 (ACE2) receptor [1, 7]. As a member of the Omicron lineage, the BA.5 spike protein contains a high density of mutations, particularly in the receptor-binding domain (RBD) and N-terminal domain (NTD), which significantly enhance its ability to evade neutralizing antibodies from prior infections and original vaccine formulations [2, 3]. Key mutations such as L452R and F486V contribute to its increased transmissibility and immune escape, making it a primary target for updated bivalent mRNA vaccines and therapeutic monoclonal antibodies [4, 9]. While many early monoclonal treatments lost efficacy against BA.5, it remains the central focus for developing broad-spectrum antivirals and next-generation immunizations aimed at controlling the COVID-19 pandemic [3, 10]. The protein's structure consists of two subunits, S1 and S2, which undergo proteolytic cleavage to facilitate the fusion of viral and host membranes [8, 11]. Understanding the antigenic shifts in the BA.5 spike is essential for monitoring viral evolution and ensuring the continued effectiveness of therapeutic interventions [6, 12].

Other names

Omicron BA.5 spike proteinSARS-CoV-2 S protein (BA.5)B.1.1.529.5 spike proteinSARS-CoV-2 spike glycoprotein (Omicron BA.5)

Monoclonal antibodies and vaccine-induced antibodies bind to the spike protein, particularly the receptor-binding domain (RBD), to neutralize the virus by preventing its interaction with the host ACE2 receptor and subsequent membrane fusion [1, 7, 11].