B-cell receptor specific for SARS-CoV-2 Membrane, Envelope, and Nucleocapsid proteins (BCR) (BCR (SARS-CoV-2 M/E/N))

B-cell receptors (BCRs) specific for the Membrane (M), Envelope (E), and Nucleocapsid (N) proteins of SARS-CoV-2 are transmembrane immunoglobulins that mediate the recognition of the virus's non-Spike structural proteins. While the Spike protein is the primary target for neutralizing antibodies, the M, E, and N proteins are highly conserved across SARS-CoV-2 variants and elicit robust B-cell responses during natural infection (PubMed: 32814599). The M protein is the most abundant structural protein and is essential for viral assembly, the E protein is a viroporin involved in viral release and pathogenesis, and the N protein packages the viral RNA genome (Nature: 10.1038/s41586-020-2852-1). BCRs targeting these proteins trigger signaling pathways that lead to B-cell activation and the secretion of antibodies that, although often non-neutralizing, contribute to viral clearance through Fc-mediated effector functions such as antibody-dependent cellular phagocytosis (ADCP) and complement activation (NIH: PMC7540712). These receptors are significant targets for multi-antigen vaccine strategies and serve as critical biomarkers for distinguishing natural infection from Spike-only vaccination.

Other names

SARS-CoV-2 M/E/N-specific B-cell receptorAnti-SARS-CoV-2 structural protein BCRNon-spike SARS-CoV-2 B-cell receptorAnti-M/E/N BCR

Recognition of specific M, E, or N epitopes by the BCR triggers intracellular signaling via the CD79a/CD79b heterodimer, leading to B-cell activation, proliferation, and differentiation into plasma cells that secrete antigen-specific antibodies.