Klebsiella pneumoniae K1 capsular polysaccharide (CPS) (K1 CPS)

Klebsiella pneumoniae K1 capsular polysaccharide (K1 CPS) is a bacterial surface polysaccharide and major virulence factor composed of repeating trisaccharide units with pyruvylation and O-acetylation modifications. The K1 capsule type is the most common serotype associated with hypervirulent K. pneumoniae strains and is the primary cause of pyogenic liver abscesses in Asia. K1 CPS functions as a protective molecular shield that enables the bacteria to evade the host immune response by blocking phagocytosis through the scavenger receptor LOX-1 and impairing dendritic cell maturation. This polysaccharide is considered an essential virulence factor, as deletion of capsule-encoding genes dramatically reduces bacterial virulence in animal models. Due to increasing antibiotic resistance in K. pneumoniae, K1 CPS has emerged as a promising therapeutic target, with research focusing on bacteriophage-derived polysaccharide lyases that can degrade the capsule and glycoconjugate vaccines that could provide protective immunity. These novel approaches represent potential alternatives to conventional antibiotic therapy.

Other names

K1 antigenK antigenCapsule polysaccharide K1

Enzymatic degradation: Bacteriophage-derived polysaccharide lyases depolymerize K1 CPS into oligosaccharide fragments while retaining important antigenic determinants (pyruvylation and O-acetylation modifications). Vaccine development: CPS-conjugated vaccines prepared using CPS depolymerases represent a promising candidate for developing vaccines against K. pneumoniae. Glycoconjugate vaccine generation: Structurally-defined oligosaccharides produced by enzymatic degradation can serve as tools to generate glycoconjugate vaccines.