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

Shigella flexneri 3a lipopolysaccharide O-antigen is a complex carbohydrate structure located on the outer membrane of the Gram-negative bacterium Shigella flexneri serotype 3a. It consists of repeating oligosaccharide units that define the serological identity of the strain and are essential for bacterial virulence. This O-antigen acts as a protective shield, helping the pathogen evade the host's innate immune system, particularly complement-mediated lysis, while facilitating the invasion of intestinal epithelial cells (1, 2). As the primary surface-exposed molecule, it is the main target for the host's adaptive immune response, specifically for the production of protective, serotype-specific antibodies (3). In clinical development, this molecule is a key target for glycoconjugate vaccines aimed at preventing shigellosis, a severe form of bacillary dysentery. These vaccines typically involve the conjugation of the O-antigen or its synthetic derivatives to a carrier protein to enhance immunogenicity and induce long-lasting memory (4, 5). Because immunity to Shigella is largely restricted to the specific O-antigen serotype, the 3a variant is included in multivalent vaccine candidates to provide broad protection against the most prevalent Shigella strains (6). Citations: (1) Perepelov AV, et al. (2010) Carbohydr Res; (2) Morona R, et al. (2003) Mol Microbiol; (3) Phalipon A, et al. (2008) J Immunol; (4) Cohen D, et al. (2023) Vaccine; (5) Micoli F, et al. (2022) Front Immunol; (6) Mani S, et al. (2016) Vaccine.

Other names

Shigella flexneri serotype 3a O-specific polysaccharideS. flexneri 3a OSPShigella flexneri 3a O-polysaccharideO-antigen of Shigella flexneri 3a

Induction of serotype-specific protective antibodies (IgG and IgA) that neutralize the pathogen and promote opsonophagocytosis or complement-mediated killing.