Uropathogenic Escherichia coli surface polysaccharides (UPEC surface polysaccharides)

Uropathogenic Escherichia coli (UPEC) surface polysaccharides, primarily the O-antigen of lipopolysaccharide (LPS) and the K-antigen of the capsular polysaccharide (CPS), are critical virulence factors that define the pathogen's interface with the host (Flores-Mireles et al., 2015). These polysaccharides form a protective physical barrier that shields the bacteria from the host's innate immune system, specifically preventing complement-mediated lysis and opsonophagocytosis (Whitfield, 2006). In UPEC, specific serotypes like O25b and K1 are strongly associated with multi-drug resistance and invasive infections such as pyelonephritis and urosepsis. These structures also serve as the primary receptors for bacteriophages, which have evolved specialized depolymerase enzymes to degrade them during infection (Lin et al., 2017). Consequently, they are major targets for therapeutic intervention, including multivalent conjugate vaccines currently in clinical trials that aim to elicit serotype-specific protective immunity (Huttner et al., 2017). However, challenges such as serotype replacement and the molecular mimicry of the K1 capsule with human neural cell adhesion molecules (NCAM) must be managed in drug development (Finne et al., 1983).

Other names

K antigenO antigenCapsular polysaccharideCPSLipopolysaccharideLPSUPEC surface antigensEscherichia coli surface polysaccharide receptors

Vaccines induce opsonophagocytic antibodies against specific O-antigens to facilitate bacterial clearance; phage-derived depolymerases enzymatically degrade the polysaccharide layer to expose the bacteria to host defenses.