Salmonella enterica serovar Typhi surface antigen (null (Vi antigen, O antigen, and H antigen are sometimes abbreviated, but no universal single abbreviation exists for all surface antigens))

Surface antigens of Salmonella enterica serovar Typhi are a collection of cell envelope structures, notably including the Vi (capsular) antigen, O antigen (LPS side chain), and H antigen (flagellar protein). The Vi antigen is a capsular polysaccharide critical for virulence and target of several typhoid vaccines[1][7]. The O antigen, a polysaccharide component of lipopolysaccharide, is immunogenic and forms the basis of serological classification and certain vaccine approaches[3][5][9]. The H antigen is a flagellar protein that is phase-variable and important for motility, epidemiology, and serotyping[2][6][7]. These antigens are crucial determinants of host immune recognition, bacterial pathogenesis, serovar classification, and are exploited in medical diagnostics and therapeutic interventions, including vaccines[1][3][7][10]. If more specificity is needed for a particular antigen or drug interaction, further molecular details can be extracted from the serotyping system and vaccine literature[2][3][5][9][10].

Other names

Vi antigen (capsular polysaccharide)O antigen (LPS surface polysaccharide)H antigen (flagellar protein)Typhi surface antigensSalmonella Typhi antigens

Vaccine-induced immune response (e.g., Vi antigen stimulates antibody production that neutralizes or opsonizes the bacteria); Direct binding and agglutination (antisera and phages bind antigens to mediate bacterial killing or detection)