Staphylococcus aureus capsular polysaccharide type 5 or type 8 (CP5 or CP8)

Staphylococcus aureus capsular polysaccharide type 5 and type 8 (CP5 and CP8) are the two predominant serotypes of the polysaccharide capsule that envelops most clinical isolates of S. aureus. These capsular polysaccharides are linear trisaccharides built from unusual monosaccharides (N-acetyl d-mannosaminuronic acid, N-acetyl l-fucosamine, and N-acetyl d-fucosamine), which differ between type 5 and type 8 only in the glycosidic linkages and sites of O-acetylation[2][5][6]. CP5 and CP8 serve as essential virulence factors: they protect S. aureus from clearance by suppressing phagocytosis and inhibiting opsonization by the host immune system, thus promoting persistent infection, abscess formation, and bloodstream survival[1][3][7]. The biosynthesis is controlled by the cap5 and cap8 operons, which encode 16 enzymes for precursor synthesis, polymerization, acetylation, and export[5][7]. Both CP5 and CP8 are attractive vaccine targets and candidate antigens for glycoconjugate vaccines under investigation because antibodies to these polysaccharides can protect against diverse S. aureus infections[2][6]. CP5 and CP8 expression can modulate immune recognition and have direct implications for the variability in S. aureus virulence. Detection of anti-CP5/CP8 antibodies, as well as the direct detection of these capsules, are used as biomarkers in studies of infection and vaccine efficacy[6]. No approved standalone therapeutic drugs target CP5/CP8, but several monoclonal antibodies and conjugate vaccine approaches are in development, aiming to neutralize capsule-mediated immune evasion and enhance bacterial clearance by the immune system[2][6].

Other names

S. aureus CP5S. aureus CP8S. aureus capsule type 5S. aureus capsule type 8Staphylococcal capsular polysaccharide type 5Staphylococcal capsular polysaccharide type 8

Induction of opsonizing antibodies that facilitate phagocytosis and bacterial clearance; Blocking capsule-mediated immune evasion; Neutralization of the polysaccharide to allow immune system recognition.