B-cell receptor recognizing Vi capsular polysaccharide (Vi-BCR)

The B-cell receptor (BCR) recognizing the Vi capsular polysaccharide is a critical component of the adaptive immune system's defense against Salmonella enterica serovar Typhi, the causative agent of typhoid fever (Source: WHO, 2018). The Vi antigen is a linear homopolymer of N-acetylgalactosaminuronic acid that covers the surface of the bacterium, masking other antigens and inhibiting phagocytosis (Source: PubMed, PMID: 28910500). When the BCR binds to this polysaccharide, it initiates the activation of B cells, leading to the production of protective anti-Vi antibodies. In the context of vaccinology, this receptor is the primary target for Vi-based vaccines, including both plain polysaccharide and protein-conjugated formulations like Typbar-TCV (Source: Lancet, 2019). Conjugate vaccines are particularly effective as they facilitate T-cell involvement, enhancing the affinity maturation and memory formation of the B cells expressing these receptors (Source: NIH, 2021). Monitoring the interaction between the Vi antigen and the BCR is essential for evaluating vaccine efficacy and understanding the mechanisms of long-term immunity against enteric fever.

Other names

Vi-specific B-cell receptorAnti-Vi B-cell receptorVi antigen receptorSalmonella Typhi Vi-specific BCR

The Vi capsular polysaccharide (or its conjugate) acts as an immunogen that binds to the B-cell receptor (BCR) on Vi-specific B cells. This binding event triggers intracellular signaling cascades that lead to B-cell activation, proliferation, and differentiation into plasma cells that secrete anti-Vi antibodies (IgM and IgG) and memory B cells, providing protective immunity against Salmonella Typhi infection.