Shigella flexneri 2a O-specific Polysaccharide

The Shigella flexneri 2a O-specific polysaccharide (O-PS) is a key component of the bacterium’s outer membrane lipopolysaccharide (LPS). It serves as the major surface antigen and is critical for serotype determination, immune recognition, and vaccine development. The O-PS consists of repeating oligosaccharide units that form the hydrophilic outermost layer of LPS, playing a central role in host-pathogen interactions and protection against environmental stress. It is a branched pentasaccharide with three L-rhamnose residues, one N-acetylglucosamine residue, and one α-D-glucose residue branching from RhaI. Antibodies targeting this polysaccharide confer protection against homologous strains. Synthetic oligosaccharides mimicking two or more consecutive pentasaccharide repeat units are required for optimal antibody recognition and mimicry of natural epitopes—important for vaccine design. Used in conjugate vaccines to enhance immunogenicity in humans.

Other names

S. flexneri 2a O-antigenShigella flexneri 2a O-PSS. flexneri type 2a O-polysaccharides

Target of antibodies; glycoconjugate vaccines stimulate antibody production against the polysaccharide