O-antigen polysaccharide and Vi capsular polysaccharide of Salmonella (anti-Salmonella antibody targets)

O-antigen polysaccharide and Vi capsular polysaccharide are major surface carbohydrate antigens of Salmonella species, functioning as critical immune targets and virulence factors. The O-antigen polysaccharide forms the serotype-defining outer part of lipopolysaccharide (LPS), composed of repeating oligosaccharide units with high structural variability that determine immunogenic specificity and resistance to host complement-mediated killing[1][5][7]. Vi capsular polysaccharide, present in Salmonella Typhi and Paratyphi C, is a distinct extracellular capsule that shields surface antigens and is a major target of protective antibodies in typhoid vaccines[1][6]. Both antigens are exploited in vaccine strategies—either as purified polysaccharides or conjugated to carrier proteins—to stimulate production of anti-Salmonella antibodies that mediate protection via opsonization, complement activation, and immune memory[6][7]. Variability in O-antigen structure among Salmonella serovars and the limited immunogenicity of unconjugated polysaccharides present challenges for vaccine development[8][1]. These bacterial polysaccharide antigens are not conventional receptors or enzymes but are validated immunological targets for prophylactic (vaccine) interventions. **Note:** This entry is marked as **is_incorrect: true** because it describes not a single molecule/receptor, but an immunological concept (antibody production targeting two different polysaccharide antigens), and includes more than one canonical target; structured information requires treatment as two entities or as a vaccine concept, not a discrete molecular target[1][6][7].

Other names

O-antigen polysaccharideO-polysaccharide antigenLipopolysaccharide O-antigenVi capsular polysaccharideVi antigen

Antibodies targeting these antigens mediate opsonization and phagocytosis, promote complement-mediated bactericidal activity, prevent bacterial attachment/invasion, and establish immunological memory via an adaptive immune response[4][6][7].