Capsular polysaccharide of Streptococcus pneumoniae serotype 11A (CPS11A)

The capsular polysaccharide of Streptococcus pneumoniae serotype 11A is a complex carbohydrate structure that serves as the primary virulence factor for this specific pneumococcal strain (NIH, 2009; Creative Diagnostics). It forms a protective outer layer that shields the bacterium from the host's immune system by inhibiting complement deposition and preventing opsonophagocytosis by neutrophils and macrophages (ResearchGate; ATCC). Structurally, the 11A polysaccharide is characterized by a unique repeating unit containing an acetylglycerol-phosphate moiety and specific O-acetylation patterns, such as beta-galactose-6-O-acetylation mediated by the wcjE gene, which are critical for its antigenic properties (NIH, 2009; NIH, 2017). This molecule is a key therapeutic target in the development of pneumococcal vaccines, including the 23-valent polysaccharide vaccine (PPV23) and newer conjugate vaccines like PCV20 and V116 (Lancet Infect Dis, 2024; ResearchGate). Vaccination induces the production of serotype-specific antibodies that neutralize the capsule's protective effect, allowing for effective bacterial clearance (ASM; NIH). However, the emergence of variants like serotype 11E, which lacks certain O-acetyl groups, poses a challenge for long-term vaccine efficacy due to potential immune escape (NIH, 2017).

Other names

Serotype 11A capsular polysaccharideS. pneumoniae 11A CPSPneumococcal polysaccharide serotype 11A11A-CPSPneumococcal polysaccharide type 11A

Induction of serotype-specific opsonophagocytic antibodies (IgG) that facilitate bacterial clearance by host phagocytes.