Salmonella Enteritidis O-specific polysaccharide (OPS)

The Salmonella Enteritidis O-specific polysaccharide is a complex, surface-exposed carbohydrate polymer that forms the distal portion of the lipopolysaccharide (LPS) on the outer membrane of Salmonella enterica serotype Enteritidis. It consists of a repeating tetrasaccharide backbone composed of mannose, rhamnose, and galactose, uniquely substituted with the rare sugar tyvelose, which defines the serovar-specific O9 (Group D1) antigen. This molecule plays a vital role in bacterial virulence by shielding the pathogen from the host's innate immune system, specifically by preventing the assembly of the complement membrane attack complex and resisting opsonophagocytosis. In the clinical and pharmaceutical sectors, the O-specific polysaccharide is the primary target for the development of glycoconjugate vaccines aimed at preventing salmonellosis and invasive nontyphoidal Salmonella (iNTS) disease. To overcome the inherent poor immunogenicity of pure polysaccharides, these targets are typically chemically linked to carrier proteins such as CRM197 or flagellin to induce a robust T-cell dependent immune response and protective IgG antibodies.

Other names

O-antigenO-polysaccharideOPSSomatic O-antigenSalmonella Enteritidis lipopolysaccharide O-antigenO-specific chainGroup D1 O-antigenO9 antigen

Stimulation of active immunity leading to the production of opsonizing IgG antibodies that enhance bacterial clearance by macrophages.