B cell receptor specific for Vi polysaccharide antigen

**B cell receptors specific for the Vi polysaccharide antigen** are membrane-bound immunoglobulins expressed on the surface of B lymphocytes that recognize and bind specifically to the Vi capsular polysaccharide of Salmonella Typhi, the causative agent of typhoid fever. The Vi antigen is a linear polymer of α-1,4-linked N-acetylgalactosaminuronic acid with variable O-acetylation, forming a capsule that is a key virulence factor and vaccine antigen[1][2]. In both mice and humans, specific B cell subsets—most notably B1b cells—are activated upon engagement with Vi antigen, leading to the production of protective anti-Vi antibodies (IgM and some IgG), a response that does not require T cell help (T-independent type II response)[4][6]. This receptor-antigen interaction underlies the mechanism of protection afforded by Vi polysaccharide and conjugate vaccines. The anti-Vi antibody response elicited serves as a biomarker for immunity and vaccine efficacy. The lack of T cell involvement in responses to unconjugated Vi polysaccharide restricts efficacy in infants and limits longevity of immunological protection, which is addressed by conjugate vaccine designs[5][6]. There are no known specific small-molecule drugs targeting these B cell receptors, but the response can be assessed for therapeutic and diagnostic purposes in typhoid vaccine studies.

Other names

Vi-specific B cell receptorVi antigen-specific B cell receptor

Activation of B cells upon recognition and binding of the Vi polysaccharide antigen, leading to production of anti-Vi antibody (primarily IgM and IgG) and generation of protective immunity[4][6]