Shigella flexneri lipopolysaccharide O-antigen (LPS O-antigen)

The **Shigella flexneri lipopolysaccharide O-antigen** is a polysaccharide chain that forms the outermost domain of the lipopolysaccharide (LPS) molecule on the surface of S. flexneri, a Gram-negative bacterial pathogen[2][6][8]. LPS consists of three covalently linked regions: lipid A (toxic anchor in the membrane), a core oligosaccharide, and the O-antigen[6][7]. The O-antigen is composed of repeating tetrasaccharide (or variant) units and is highly variable among serotypes, determining the bacterium's serological type and influencing immune recognition[8]. It acts as a major virulence factor by protecting the bacteria from phagocytosis, complement-mediated lysis, and environmental stresses (such as acid resistance in the stomach)[5][6]. The O-antigen is the primary target for protective antibodies and the focus of vaccine development efforts; synthetic fragments of the O-antigen can elicit specific and protective immune responses[1]. Its expression and chain length are regulated by dedicated bacterial enzymes (e.g., Wzz family proteins), and alterations in O-antigen structure or biosynthesis affect virulence and immune evasion[2][3][4][8]. Endotoxin activity is mainly attributed to the lipid A portion, but O-antigen structure modulates host immune interactions, explaining its significance as a vaccine antigen and immune biomarker[6][7].

Other names

Shigella flexneri O-antigenShigella flexneri LPS O-antigenO-antigen of Shigella flexneriO-polysaccharide of Shigella flexneriS. flexneri lipopolysaccharide O-antigen

Antibody-mediated neutralization (monoclonal antibodies recognize O-antigen epitopes for immune clearance)[1] Immunogenic mimicry (synthetic oligosaccharides or glycoconjugate vaccines elicit protective immunity)[1] Vaccine-targeted antigen (elicits host immune response)[1]