Klebsiella pneumoniae K1 capsular polysaccharide antigen

The Klebsiella pneumoniae K1 capsular polysaccharide antigen is a high-molecular-weight glycan polymer forming the outermost layer (capsule) of K. pneumoniae strains belonging to the K1 serotype. This structure is composed of repeating units of monosaccharides—such as mannose, glucose, and galactose—often modified by pyruvate and O-acetylation, which enhance its immunogenicity and virulence[1]. The K1 capsular antigen is the primary virulence determinant, providing resistance to complement-mediated killing by masking bacterial surface molecules and suppressing the host’s inflammatory response[1][3]. K1 CPS is essential for the pathogenesis of severe K. pneumoniae infections, including pyogenic liver abscess and invasive community-acquired diseases[3]. The K1 polysaccharide is a promising vaccine target; conjugate vaccines and monoclonal antibodies against K1 CPS have demonstrated bactericidal activity and protection in preclinical models, but no clinical vaccine is yet available[2][3]. High CPS variability among strains presents challenges for broad-spectrum vaccine development[2][4].

Other names

K1 capsular antigenK1 CPSKlebsiella pneumoniae capsular antigen K1K1 capsule

Induction of protective anti-capsular antibodies (for vaccines and monoclonal antibodies targeting K1 CPS)