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.