Streptococcus pneumoniae common cell wall polysaccharide (C-ps) (C-ps)

The Streptococcus pneumoniae common cell wall polysaccharide, often abbreviated as C-ps, is a complex teichoic acid that is covalently linked to the peptidoglycan of the bacterial cell wall (Fischer, 1994). Unlike the capsular polysaccharides which vary by serotype, C-ps is highly conserved across all strains of S. pneumoniae, making it a universal marker for the species (Sorensen et al., 1990). A defining feature of C-ps is the presence of phosphorylcholine (PC) residues, which are essential for anchoring various choline-binding proteins (CBPs) that regulate cell wall growth and autolysis (Tomasz, 1967). These PC residues also serve as the primary binding site for human C-reactive protein (CRP), an innate immune system component that activates the classical complement pathway upon recognition of the bacterium (Tillett & Francis, 1930). In clinical settings, C-ps is the target of rapid diagnostic tests, such as the urinary antigen assay, which allows for the quick identification of pneumococcal pneumonia (Moore et al., 2003). While not the primary focus of current conjugate vaccines, which target the capsule, C-ps remains a subject of research for potential universal vaccine strategies due to its conservation (Briles et al., 1992). It also plays a role in bacterial adhesion to host cells by interacting with the platelet-activating factor (PAF) receptor (Cundell et al., 1995). Understanding the interactions of C-ps is crucial for both the development of diagnostic tools and the study of pneumococcal pathogenesis and host defense mechanisms.

Other names

C-polysaccharidePneumococcal C-substanceCell wall teichoic acidCWTAC-substanceC-ps

The common cell wall polysaccharide serves as a target for the innate immune system through C-reactive protein (CRP) binding to phosphorylcholine residues, which triggers the classical complement pathway (Tillett & Francis, 1930; Volanakis, 1981). In diagnostic applications, it acts as the primary antigen for monoclonal antibodies in rapid immunochromatographic tests used to detect pneumococcal infection in urine or CSF (Moore et al., 2003). In the context of immunization, it can induce antibodies that provide broad, though often non-protective, cross-reactivity across pneumococcal serotypes (Briles et al., 1992).