Shigella antigen

Shigella antigens are the molecular components of the Gram-negative Shigella species that mediate bacterial virulence and are the primary focus of host immune recognition. The most critical antigens for therapeutic and vaccine development are the lipopolysaccharide (LPS) O-antigen (or O-specific polysaccharide) and the invasion plasmid antigens (Ipa proteins), such as IpaB, IpaC, and IpaD. The O-antigen is the basis for Shigella serotyping and the primary driver of serotype-specific immunity, making it the central component of glycoconjugate vaccines like Flexyn2a and S4V2. The Ipa proteins are essential components of the Type III secretion system (T3SS) used by the bacteria to invade the intestinal epithelium and escape phagosomes, representing attractive targets for cross-protective vaccines due to their high conservation across serotypes. Current drug development efforts focus on inducing high titers of serum IgG and mucosal IgA against these antigens to neutralize the pathogen and prevent shigellosis, a leading cause of global diarrheal mortality. By targeting these surface and secreted components, these interventions aim to block bacterial attachment, cellular entry, and the subsequent inflammatory colitis characteristic of the disease.

Other names

Shigella antigensShigella O-antigenLipopolysaccharide O-specific polysaccharideO-antigen (OAg)Invasion plasmid antigensIpa proteinsO-specific polysaccharide (OSP)Type III secretion system (T3SS) proteins

Induction of neutralizing and bactericidal antibodies (IgG and IgA) that target surface O-antigens or the Type III secretion system (Ipa proteins) to prevent bacterial adhesion and epithelial invasion.