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

The B-cell receptor recognizing Salmonella Typhi Vi capsular polysaccharide is a membrane-bound immunoglobulin complex on B lymphocytes that specifically identifies the Vi (Virulence) antigen, a linear homopolymer of N-acetylgalactosaminuronic acid essential for the pathogenicity of Salmonella Typhi (WHO, 2018). This receptor plays a central role in the adaptive immune response by initiating the signaling pathways required for B-cell activation and differentiation into plasma cells that secrete protective antibodies (Lyle et al., 2020). Recognition of the Vi antigen by the B-cell receptor is the primary mechanism by which typhoid vaccines, such as the Vi-polysaccharide and Vi-conjugate vaccines, confer protection against typhoid fever (Pollard et al., 2017). Unlike plain polysaccharide vaccines, conjugate vaccines facilitate T-cell-dependent activation of these B-cell receptors, leading to higher affinity antibodies and the establishment of long-term immune memory (Jin et al., 2017). The interaction is highly specific to the O-acetylation status of the Vi polysaccharide, which is a critical determinant of epitope recognition by the receptor (Voysey et al., 2018). Monitoring the frequency and activation state of B cells expressing this receptor serves as a vital biomarker for assessing vaccine immunogenicity and the duration of protection in clinical trials (Meiring et al., 2021).

Other names

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

Binding of the Vi antigen to the B-cell receptor triggers intracellular signaling that leads to B-cell activation, clonal expansion, and the secretion of specific antibodies to neutralize Salmonella Typhi.