Salmonella Enteritidis O-antigen

The **Salmonella Enteritidis O-antigen** is a structurally variable, surface-exposed polysaccharide forming the distal part of lipopolysaccharide (LPS) molecules in the outer membrane of *Salmonella enterica* serovar Enteritidis[1][2][3][5]. It consists of repeated oligosaccharide units (the chemical structure can include sugars like mannose, rhamnose, galactose, with serovar-defining side chains and decorations[3][5]). The O-antigen is a key antigenic determinant used in serotyping and a major virulence factor that enables Salmonella to evade host immune responses, resist serum complement, and persist in infection[1][2][5]. Its biosynthesis is genetically encoded (typically on the Salmonella chromosome, e.g., at the rfb locus), involving pathways like Wzx/Wzy-dependent synthesis and additional modifications by various enzymes[1][3][5]. The O-antigen serves as a primary target for the host immune system—antibody responses against it are protective, making it a principal component in the development of vaccines (including conjugate/glycoengineered vaccines and GMMA-based OMV vaccines)[5].

Other names

O-antigen (of Salmonella Enteritidis)O-polysaccharideOPSO-specific polysaccharideLPS O-antigen (in the context of lipopolysaccharide)

Antibody targeting: Antibodies bind O-antigen, leading to complement-mediated killing or opsonization[2][5] Vaccine-induced immunity: Induced generation of protective antibodies against exposed O-antigen[5]