Shigella flexneri serotype 1b lipopolysaccharide O-antigen (S. flexneri 1b O-antigen) (S. flexneri 1b O-antigen)

Shigella flexneri serotype 1b lipopolysaccharide O-antigen is a surface-exposed polysaccharide that constitutes the outermost part of the lipopolysaccharide (LPS) layer in the Gram-negative bacterium Shigella flexneri [4, 10]. It is composed of a repeating tetrasaccharide unit consisting of three L-rhamnose residues and one N-acetylglucosamine, with specific O-acetylation at the RhaI residue and glucosylation at the RhaII residue defining the 1b serotype [7, 12]. This molecule plays a vital role in bacterial pathogenesis by facilitating cell-to-cell spread, providing resistance to environmental stresses like stomach acid, and aiding in immune evasion [4, 11]. As the primary target for protective humoral immunity, the 1b O-antigen is a central component in multivalent vaccine candidates, including glycoconjugates and Generalized Modules for Membrane Antigens (GMMA) [1, 12, 14]. These vaccines aim to elicit serotype-specific bactericidal antibodies to prevent shigellosis, a major cause of bacillary dysentery and childhood mortality in low-resource settings [8, 14]. Therapeutic challenges include the high diversity of Shigella serotypes and the need for broad-spectrum coverage to prevent serotype replacement [1, 12].

Other names

Shigella flexneri 1b O-polysaccharideS. flexneri 1b O-AgShigella flexneri serotype 1b LPS O-antigenSomatic antigen 1b

Induction of protective humoral immunity, specifically anti-O-antigen IgG, which provides serotype-specific protection through serum bactericidal activity and the blocking of bacterial invasion into the colonic epithelium [8, 12, 14].