Shigella flexneri serotype 3a lipopolysaccharide O-antigen (S. flexneri 3a O-antigen)

Shigella flexneri serotype 3a lipopolysaccharide (LPS) O-antigen is a key surface-exposed carbohydrate component of the outer membrane of the Gram-negative bacterium S. flexneri (Perepelov et al., 2009, Carbohydrate Research). It is composed of repeating oligosaccharide units consisting of a rhamnose-based backbone with specific glucosylation and O-acetylation modifications that define its serological identity (Sun et al., 2012, Journal of Bacteriology). This molecule plays a vital role in bacterial pathogenesis by providing a physical barrier against host innate immune factors and facilitating the invasion of colonic epithelial cells (West et al., 2005, Molecular Microbiology). As a major target of the host's protective immune response, the O-antigen is the primary focus for the development of shigellosis vaccines, including glycoconjugates and synthetic carbohydrate vaccines (Mani et al., 2016, Frontiers in Immunology). Therapeutic strategies targeting this O-antigen aim to induce high titers of specific antibodies that can neutralize the pathogen and prevent the severe inflammatory diarrhea characteristic of shigellosis. Given the diversity of Shigella serotypes, the 3a O-antigen is often included in multivalent vaccine formulations to ensure broad protection against prevalent strains (Cohen et al., 2022, The Lancet Infectious Diseases).

Other names

Shigella flexneri 3a O-polysaccharideS. flexneri 3a LPS O-antigenShigella flexneri serotype 3a O-AgO-antigen of S. flexneri 3a

Induction of serotype-specific protective antibodies (IgG and IgA) that mediate opsonophagocytosis and complement-mediated killing of the bacteria (Cohen et al., 2022, The Lancet Infectious Diseases).