Pneumococcal surface protein A (PspA) (PspA)

Pneumococcal surface protein A (PspA) is a vital surface-exposed virulence factor and choline-binding protein expressed by virtually all strains of Streptococcus pneumoniae. Its primary biological function is to facilitate immune evasion by inhibiting the deposition of complement C3b on the bacterial surface, thereby preventing opsonophagocytosis by host immune cells. PspA also binds to host lactoferrin, protecting the pathogen from the bactericidal effects of apolactoferrin, and serves as an adhesin by interacting with host glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The PRx1 designation refers to a specific recombinant variant of PspA derived from the laboratory strain Rx1, which belongs to PspA Family 1 (Clade 2). Because PspA is highly immunogenic and antibodies against it can provide cross-protection across different pneumococcal serotypes, it is a leading candidate for next-generation protein-based vaccines aimed at overcoming the limitations of current polysaccharide-conjugate vaccines.

Other names

Pneumococcal surface protein APspAPspA/Rx1PRx1PspA Family 1 Clade 2

Vaccine-mediated induction of antibodies that neutralize PspA virulence functions, thereby enhancing complement-mediated opsonophagocytosis and clearance of Streptococcus pneumoniae.