Salmonella Typhi Vi Capsular Polysaccharide Antigen (Vi antigen)

The Vi capsular polysaccharide antigen is a surface-expressed linear polymer found on *Salmonella enterica* serovar Typhi, the causative agent of typhoid fever. It is a major virulence factor, acting as an antiopsonic and antiphagocytic shield, reducing phagocytosis by neutrophils while promoting uptake by macrophages; it also increases resistance to oxidative killing by immune cells. It suppresses host immune responses by targeting membrane prohibitin proteins and masking pathogen-associated molecular patterns (PAMPs), helping *S. Typhi* evade innate immunity. Vaccination with purified Vi polysaccharide induces protective antibodies primarily through T cell-independent B cell responses.

Other names

Vi capsular polysaccharideVi polysaccharide antigenVi CPS

Vaccination with Vi polysaccharide induces protective antibodies primarily through T cell-independent B cell responses, leading to immunity against *S. Typhi* expressing the Vi antigen.