Streptococcus pneumoniae capsular polysaccharide serotype 6C (Spn6C CPS) (Spn6C CPS)

Streptococcus pneumoniae capsular polysaccharide serotype 6C is a complex carbohydrate polymer that constitutes the protective outer capsule of the 6C pneumococcal strain. Discovered in 2007, this serotype was previously misidentified as 6A due to their structural similarity; however, 6C contains glucose instead of galactose in its repeating unit, a change mediated by the wciN gene (Park et al., 2007, J Clin Microbiol). The polysaccharide acts as a primary virulence factor by inhibiting phagocytosis and preventing complement deposition, thereby allowing the bacterium to evade the host immune system (Cooper et al., 2011, Vaccine). As a therapeutic target, it is utilized in conjugate vaccines to stimulate the production of opsonophagocytic antibodies. While not explicitly included in the 13-valent pneumococcal conjugate vaccine (PCV13), the 6A component in PCV13 provides significant cross-protection against 6C (CDC, 2023). Newer formulations like PCV15 and PCV20 continue to target this serotype to reduce the burden of invasive pneumococcal diseases such as pneumonia, meningitis, and bacteremia (FDA, 2021).

Other names

Pneumococcal polysaccharide serotype 6CS. pneumoniae 6C antigenSerotype 6C capsular polysaccharideCPS 6C

Induction of serotype-specific opsonophagocytic antibodies to facilitate bacterial clearance.