Salmonella Typhi antigen (null)

"Salmonella Typhi antigens" is a collective term for the major pathogen-associated molecular structures present on the surface of Salmonella enterica serovar Typhi, the causative agent of typhoid fever. The principal antigens include the **O-antigen** (part of the lipopolysaccharide/LPS), which is a polysaccharide forming the outermost part of the bacterial envelope and confers serovar specificity[3][5][7][9]; the **Vi (virulence) capsular polysaccharide antigen**, which overlays the O-antigen and is a hallmark of S. Typhi[2][8]; and the **H antigen**, corresponding to flagellin proteins encoded by the fliC and fljB genes (classic variants: H:d, H:j, H:z66)[4][6]. Additional antigens include outer-membrane proteins like **ST50**, which are targets for both diagnostics (e.g., Typhidot™ kit) and potential therapeutic antibodies[1]. These antigens have key roles in the **immune response** (they are highly immunogenic and recognized by both innate and adaptive immunity), disease pathogenesis, and serve as **biomarkers** in diagnosis and as functional targets for vaccines. However, antigenic and genetic variability between strains and phase variation in antigen expression present challenges for both vaccine efficacy and accurate diagnosis[3][4][7]. No single molecule is the universal target; 'Salmonella Typhi antigen' refers to a set of molecular patterns used for serotyping, diagnostics, and immune recognition[2][4][3]. Clarification: The query target "Salmonella Typhi antigens" refers to a heterogeneous group of biomolecules (O-antigen, Vi antigen, etc.), not a single defined receptor or protein. Therefore, this entry is technically **incorrect as a singular drug target**, but accurate as a composite set of immunological and diagnostic targets. Each antigen (O-antigen, Vi capsule, H flagellin, etc.) may merit its own canonical entry for precise drug-target information.

Other names

S. Typhi antigenTyphoid antigenSalmonella enterica serovar Typhi antigen

Induction of adaptive immunity (vaccines targeting O-antigen, Vi antigen, or flagellin); Antibody-mediated neutralization (diagnostic and therapeutic antibodies against specific antigens); Bactericidal activity via immune-mediated clearance