Lipopolysaccharide from Shigella flexneri serotype 2a (LPS (S. flexneri 2a))

Lipopolysaccharide (LPS) from Shigella flexneri serotype 2a is a major glycolipid component of the bacterial outer membrane consisting of three parts: lipid A, core oligosaccharide, and highly variable O-polysaccharide (O-antigen). In S. flexneri 2a, the O-antigen is a repeating pentasaccharide, distinctive for its unique branching glucose residues and defined chain lengths; it is a key virulence factor, critical for acid resistance, immune evasion, and initiation of infection in humans. LPS acts as the principal immunogen in vaccine development against Shigella flexneri 2a and is the main determinant of serotype-specific immunity, but can also trigger severe inflammatory responses via the TLR4 pathway, especially if not chemically detoxified. Additionally, the composition and structure of LPS influence the interaction with bacteriophages and the degree of virulence and immune modulation by the bacterium.

Other names

Shigella flexneri serotype 2a LPSS. flexneri 2a O-antigenS. flexneri 2a O-PS (O-polysaccharide)Shigella O antigen 2a

For drugs and vaccines: - Vaccines using O-antigen polysaccharide fragments induce specific antibodies that bind to LPS, promoting opsonization, complement activation, and bacterial clearance. - Monoclonal antibodies against LPS block infection and confer serotype-specific immunity by sterically hindering bacterial attachment or function. - LPS modifications (e.g., hypoacylation) can modulate TLR4-mediated signaling and dampen host inflammatory responses.