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

The Vi capsular polysaccharide-specific B-cell receptor is a membrane-bound immunoglobulin complex expressed on the surface of B lymphocytes that specifically recognizes the Vi (Virulence) capsular polysaccharide of Salmonella enterica serovar Typhi (S. Typhi). This receptor is the primary mediator of the humoral immune response against typhoid fever, as its engagement by the Vi antigen triggers B-cell activation, clonal expansion, and differentiation into antibody-secreting plasma cells (Pollard et al., 2017, Lancet). In the context of preventative medicine, this receptor is the biological target for Vi-based vaccines, including plain polysaccharide vaccines and Vi-conjugate vaccines (WHO, 2018). While plain polysaccharides act as T-cell independent antigens that cross-link these receptors to induce a relatively short-lived response, conjugate vaccines facilitate T-cell help, leading to higher affinity maturation of the receptor progeny and the generation of long-lived memory B cells (Cross et al., 2020, NPJ Vaccines). Monitoring the frequency and activation state of B cells expressing this specific receptor serves as a critical biomarker for assessing vaccine immunogenicity and the duration of protection in clinical trials.

Other names

Vi-specific B-cell receptorSalmonella Typhi Vi antigen receptorVi-polysaccharide B-cell receptor

Antigen-induced B-cell receptor signaling and activation leading to the production of protective anti-Vi antibodies.