Salmonella enterica serovar Paratyphi A O:2 lipopolysaccharide (Paratyphi A O:2 LPS)

Salmonella enterica serovar Paratyphi A O:2 lipopolysaccharide (LPS) is a major surface antigen and essential virulence factor of the bacterium responsible for paratyphoid fever [NIH, 2021; ResearchGate, 2021]. The LPS molecule consists of three regions: lipid A, a core oligosaccharide, and the O-specific polysaccharide (O-antigen) [Bio-Rad, 2024]. The O:2 antigen is characterized by a trisaccharide backbone of rhamnose, mannose, and galactose, with a unique paratose branch that defines its serogroup specificity [NIH, 2021; NIH, 2025; NIH, 1996]. As the immunodominant portion of the bacterial surface, the O:2 LPS is the primary target for the development of conjugate vaccines, where the polysaccharide is linked to carrier proteins like CRM197 or tetanus toxoid to induce a T-cell dependent immune response [NIH, 2021; WHO, 2024]. These vaccines aim to elicit high titers of bactericidal antibodies to prevent systemic infection [NIH, 2021; NIH, 1996]. Currently, there are no licensed vaccines specifically for Paratyphi A, making this molecule a critical focus for global health initiatives to combat enteric fever [WHO, 2024; NIH, 2022].

Other names

O:2 antigenO-specific polysaccharideO-antigenParatyphi A O-SPO:2-LPSSalmonella Paratyphi A O-polysaccharide

Induction of protective antibodies (IgG and IgA) against the O:2 antigen, which provide bactericidal and opsonophagocytic activity [NIH, 2021; NIH, 1996].