Salmonella Paratyphi A O-specific Polysaccharide Antigen (Paratyphi A OSP)

The O-specific polysaccharide (OSP) antigen of *Salmonella enterica* serovar Paratyphi A is a key component of the bacterium’s lipopolysaccharide (LPS), which is a major constituent of the outer membrane in Gram-negative bacteria. The OSP forms the outermost part of LPS and plays a critical role in immune recognition, virulence, and as a target for vaccine development. The OSP consists of repeating oligosaccharide units that extend from the conserved core region of LPS. It is composed primarily of a trisaccharide backbone (rhamnose, mannose, and galactose) with branches of d-paratose and glucose. Partial O-acetylation at the C-3 position on rhamnose is also present. Antibodies against the OSP can mediate bactericidal activity and are considered protective. Conjugate vaccines using detoxified or isolated S. Paratyphi A OSP linked to carrier proteins have shown promising results. It defines serogroup A within Salmonella species.

Other names

S. Paratyphi A O-antigenSalmonella Paratyphi A OSPGroup A Salmonella O-specific Polysaccharide

Antibodies targeting the OSP mediate bactericidal activity.