Shigella sonnei O-antigen lipopolysaccharide (S. sonnei O-antigen LPS)

Shigella sonnei O-antigen lipopolysaccharide is a structurally distinct, strain-specific glycolipid forming the outermost part of *S. sonnei*’s outer membrane. Its O-antigen is a polymer of two unusual sugars, 2-acetamido-2-deoxy-L-altruronic acid (L-AltNAcA) and 2-acetamido-2-deoxy-L-fucose (FucNAc4N), not commonly found in other bacteria[3][5][7]. The O-antigen, linked via the core oligosaccharide to lipid A, serves as an immunodominant and protective antigen, facilitating immune evasion and contributing to pathogenesis[1][3][5]. The O-antigen’s unique and highly immunogenic structure makes it an ideal target for vaccines and monoclonal antibodies, which can protect against *Shigella sonnei* infection by promoting bacterial clearance without substantial toxicity if the lipid A moiety is modified[2][7][8]. Its presence and length affect bacterial interaction with phagocytes and susceptibility to host immune responses[3][5].

Other names

S. sonnei O-antigenS. sonnei OAgShigella sonnei O-polysaccharideShigella sonnei O somatic antigenS. sonnei LPS O-antigen

Antibodies binding to O-antigen promote immune-mediated killing (complement activation, opsonization) Vaccine-induced antibodies block invasion of host cells and promote clearance