The Lipopolysaccharide of Shigella Bacteria as a Virulence Factor

The virulence factors of the lipopolysaccharide of Shigella species bacteria include the endotoxic activities of the lipid A component of the molecule and the ability of the polysaccharide chain — the core and the O-antigenic polysaccharide — to provide the bacterium with resistance to host defense mechanisms such as opsonization, phagocytosis, and intracellular killing. Structural features of the lipopolysaccharides of four Shigella species—S. dysenteriae, S. flexneri, S. boydii, and S. sonnei—are described.