Severe acute respiratory syndrome coronavirus 2 B.1.351 variant spike protein (SARS-CoV-2 B.1.351 S protein)

The Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) B.1.351 variant spike protein, also known as the Beta variant antigen, is the primary surface glycoprotein responsible for viral attachment and entry into host cells. This variant is characterized by multiple mutations in the receptor-binding domain (RBD), most notably K417N, E484K, and N501Y, which enhance its binding affinity for the human angiotensin-converting enzyme 2 (ACE2) receptor (Tegally et al., 2021). These structural alterations allow the virus to partially evade the immune system by reducing the neutralization efficacy of antibodies generated from prior infections or ancestral-strain vaccines (Wang et al., 2021). The B.1.351 variant was first identified in South Africa and was designated a "variant of concern" due to its potential for increased transmissibility and significant immune escape (WHO, 2021). As a therapeutic target, the B.1.351 spike protein is used in the development of updated mRNA vaccines and specialized monoclonal antibodies designed to block the RBD-ACE2 interaction. Some early monoclonal antibody therapies, such as Bamlanivimab, exhibited significantly reduced potency against this specific variant antigen due to the E484K mutation (CDC, 2021). Effective drugs targeting this antigen include neutralizing antibodies like Sotrovimab, although the ongoing evolution of the virus necessitates constant monitoring of therapeutic efficacy. Monitoring titers of neutralizing antibodies against this variant serves as a key biomarker for evaluating vaccine performance and patient immunity levels.

Other names

Beta variant antigen501Y.V2VOC-20DEC-02South African variant spike proteinBeta variant spike protein

Neutralization of viral entry by blocking the interaction between the viral spike protein receptor-binding domain (RBD) and the host cell angiotensin-converting enzyme 2 (ACE2) receptor.