Pneumococcal capsular polysaccharide serotype 1 (CPS1)

Pneumococcal capsular polysaccharide serotype 1 is a major virulence factor and surface antigen of the bacterium Streptococcus pneumoniae serotype 1 [5, 6]. It forms a thick, protective capsule that encapsulates the bacterial cell, shielding it from the host's innate immune system by inhibiting complement-mediated opsonization and subsequent phagocytosis by neutrophils and macrophages [6, 8]. Unlike most other pneumococcal polysaccharides, serotype 1 possesses a unique zwitterionic chemical structure, which allows it to function as a T-cell dependent antigen, a rare property among bacterial polysaccharides [1]. Clinically, this serotype is a leading cause of invasive pneumococcal disease (IPD), including pneumonia, meningitis, and bacteremia, and is frequently associated with complications like empyema and outbreaks in closed communities [1, 3, 5]. It serves as a primary target for both polysaccharide and conjugate vaccines, such as Pneumovax 23 and Prevnar 20 [4, 7, 21]. These vaccines work by inducing the production of specific opsonophagocytic antibodies that neutralize the capsule's protective effects, thereby facilitating the clearance of the pathogen by the immune system [2, 10, 25].

Other names

Streptococcus pneumoniae type 1 capsular polysaccharide antigenSp1Pneumococcal polysaccharide serotype 1CPS type 1

Induction of active immunity through the production of serotype-specific opsonophagocytic antibodies that facilitate bacterial clearance by host phagocytes.