Staphylococcus aureus capsular polysaccharide (CP (commonly CP5 or CP8 for major serotypes))

Staphylococcus aureus capsular polysaccharide is a surface-exposed linear or branched polysaccharide structure synthesized by S. aureus, functioning as a key virulence factor that encases the bacterium to evade innate immune clearance, particularly by inhibiting phagocytosis by neutrophils and macrophages[1][5][9]. Most clinically relevant S. aureus isolates express type 5 or type 8 capsules (CP5, CP8), each composed of serotype-specific repeating units of unusual aminosugars and uronic acids, often O-acetylated for immune evasion[2][4][7][8]. Capsule biosynthesis is encoded by allelic cap gene clusters (cap5, cap8), strictly regulated at the transcriptional level in response to environmental stimuli[5]. Capsular polysaccharides are prominent candidates for vaccine antigens because antibodies directed against them promote opsonization and facilitate bacterial clearance; however, antigenic diversity and immune regulation are challenges for vaccine efficacy[1][2][4][9]. While not essential for in vitro growth, capsules play a central role in pathogenesis, particularly in abscess and invasive infection, and have been used to develop conjugate and multivalent vaccine candidates for both human and veterinary medicine[2][5][9].

Other names

S. aureus capsuleStaphylococcal capsuleCapsular polysaccharide (CP)S. aureus CP5S. aureus CP8

Induction of protective antibodies by vaccination, promoting opsonization and phagocytic clearance of encapsulated S. aureus; Potential use of monoclonal antibodies to neutralize virulence