Salmonella enterica serovar Typhimurium O-antigen polysaccharide (O-antigen)

The Salmonella enterica serovar Typhimurium O-antigen polysaccharide is the highly variable, serotype-defining polysaccharide component of the lipopolysaccharide (LPS) that forms the outermost surface of the bacterium. This O-antigen consists of repeating oligosaccharide units built on a core-lipid A structure, with each strain or serovar displaying a distinct composition and linkage pattern that determines serological identity (e.g., O:4 in S. Typhimurium). The O-antigen is critical for bacterial survival in the host, mediating resistance against complement-mediated killing and modulating surface antigenicity to evade immune detection. It is the principal antigenic target for serotyping and serves as the main target for vaccine development, although structural diversity and phase variation pose challenges for vaccine design and efficacy. There are currently no approved drugs directly targeting this polysaccharide, but it is central to several candidate subunit and conjugate vaccine strategies.

Other names

O-antigenO-antigen polysaccharideLPS O-antigenSalmonella Typhimurium O-antigenGroup B O-antigen (O:4 serotype)

Induction of protective antibodies (vaccine mechanism); Antibodies target O-antigen to promote bacterial killing and immune clearance