Salmonella enterica serovar Enteritidis O:9 O-antigen polysaccharide (SE O-antigen)

The Salmonella enterica serovar Enteritidis O:9 O-antigen polysaccharide is a critical structural component of the outer membrane lipopolysaccharide (LPS) in Group D Salmonella. It consists of a repeating oligosaccharide unit typically composed of a backbone of alpha-D-mannose, alpha-L-rhamnose, and alpha-D-galactose, with a unique 3,6-dideoxyhexose sugar called tyvelose attached to the mannose residue, which defines the O:9 serospecificity (Micoli et al., 2014, Vaccine). This polysaccharide plays a vital role in bacterial virulence by protecting the pathogen from the host's innate immune system, specifically preventing complement-mediated killing and phagocytosis (Fehervari et al., 2022, Frontiers in Immunology). As a primary surface-exposed target, the O:9 antigen is the focus of vaccine development efforts aimed at preventing non-typhoidal Salmonella infections, which are a leading cause of global foodborne gastroenteritis. Because pure polysaccharides are often poorly immunogenic in infants, therapeutic strategies involve conjugating the O-antigen to carrier proteins to induce a T-cell dependent immune response and long-term memory (MacLennan et al., 2014, Human Vaccines & Immunotherapeutics). Clinical and preclinical studies utilize these glycoconjugates to elicit high titers of bactericidal antibodies, providing a protective barrier against Salmonella Enteritidis colonization and systemic spread.

Other names

Salmonella Enteritidis O-polysaccharideGroup D1 O-antigenO:9 antigenSalmonella Enteritidis lipopolysaccharide O-side chain

Induction of protective humoral immunity through the production of O-antigen-specific bactericidal antibodies that promote opsonophagocytosis and complement-mediated lysis of the bacteria.