O-polysaccharide of Pseudomonas aeruginosa

The O-polysaccharide of Pseudomonas aeruginosa is the distal, highly variable polysaccharide domain of the bacterium's lipopolysaccharide (LPS), which forms the outer leaflet of the outer membrane in this Gram-negative pathogen[1][3][5]. The O-polysaccharide, or O-antigen, exists in two primary forms in most P. aeruginosa strains: the common polysaccharide antigen (CPA, previously A band), which is a homopolymer of D-rhamnose, and the O-specific antigen (OSA, previously B band), which is a heteropolymer consisting of unique and often rare sugar residues with varying repeat unit lengths and saccharide composition depending on the serotype[1][5]. O-polysaccharide determines serotype, is key for immune evasion and serum resistance, enables the bacteria to avoid host defenses, contributes to biofilm formation, enhances virulence, and is a major determinant in chronic and persistent infections, notably in cystic fibrosis lungs[1][3][7]. While not a receptor or protein target, it is the focus of vaccine, antibody, and bacteriophage-based antimicrobial strategies that aim to disrupt its protective functions or facilitate immune clearance[5][6]. Its considerable heterogeneity and ability to be lost or modified by the pathogen present significant challenges for therapeutic targeting and vaccine development[1][5][7].

Other names

O antigen of Pseudomonas aeruginosaO-specific antigen of Pseudomonas aeruginosaO-polysaccharide antigenCommon polysaccharide antigen (CPA, formerly A band)O-specific antigen (OSA, formerly B band)B-band polysaccharide

Bacteriophage or enzyme therapies: degradation of O-antigen chains to sensitize bacteria to immune systems and reduce virulence[5]. Antibody-based: target O-specific antigen to mediate opsonization and promote bacterial clearance.