O-specific polysaccharide of Shigella sonnei lipopolysaccharide (S. sonnei O-SP)

The O-specific polysaccharide (O-SP) of Shigella sonnei lipopolysaccharide is the primary surface antigen and a critical virulence factor for this Gram-negative bacterium (Nature Reviews Microbiology, 2016). Unlike other Shigella species, S. sonnei exists as a single serotype, characterized by a unique repeating disaccharide unit composed of 2-acetamido-2-deoxy-L-altruronic acid and 2-acetamido-2,6-dideoxy-D-glucose (European Journal of Biochemistry, 1971). This polysaccharide chain extends from the bacterial outer membrane, providing a physical barrier against host complement-mediated killing and facilitating intestinal colonization (Frontiers in Cellular and Infection Microbiology, 2018). In therapeutic development, the O-SP is the central target for various vaccine candidates, including bioconjugates like Flexyn2a and Generalized Modules for Membrane Antigens (GMMA) like 1790GAHB, designed to elicit protective IgG antibodies (The Lancet Infectious Diseases, 2019). Clinical efficacy is typically measured by the induction of serum bactericidal activity and O-SP-specific antibody titers, which correlate with protection against shigellosis (Vaccine, 2017). Targeting this molecule aims to provide long-term immunity against bacillary dysentery, particularly in endemic regions and for travelers (PLOS Neglected Tropical Diseases, 2021).

Other names

Shigella sonnei O-antigenS. sonnei O-polysaccharideShigella sonnei LPS O-chain

Active immunization to elicit O-antigen-specific bactericidal IgG antibodies that facilitate opsonophagocytosis and complement-mediated killing of Shigella sonnei.