Escherichia coli O-antigen polysaccharide (O-antigen)

The Escherichia coli O-antigen polysaccharide is the distal, surface-exposed component of the lipopolysaccharide (LPS) found on the outer membrane of Gram-negative bacteria [1]. It consists of repeating oligosaccharide units whose composition and arrangement vary widely, defining the O-serogroup of the strain [2]. Biologically, the O-antigen serves as a critical protective barrier against host innate immune responses, specifically preventing the assembly of the membrane attack complex (MAC) and resisting phagocytosis [3]. In clinical contexts, specific O-antigens are associated with virulent pathotypes, such as Extra-intestinal Pathogenic E. coli (ExPEC) causing sepsis and urinary tract infections, or Enterohemorrhagic E. coli (EHEC) like O157:H7 [4]. As a therapeutic target, O-antigens are the primary focus for the development of glycoconjugate vaccines, which aim to elicit opsonophagocytic antibodies to provide serotype-specific immunity [5]. Additionally, monoclonal antibodies and bacteriophages utilize the O-antigen as a primary receptor for binding and infection, respectively [6]. Sources: [1] Raetz and Whitfield (2002) Annu Rev Biochem; [2] Stenutz et al. (2006) FEMS Microbiol Rev; [3] Liu et al. (2020) Front Microbiol; [4] Poolman and Wacker (2016) Vaccine; [5] Frenck et al. (2019) Vaccine; [6] Morita et al. (2002) J Bacteriol.

Other names

O-polysaccharideO-specific chainO-side chainLPS O-antigenO-antigenic polysaccharideOPS

Induction of opsonophagocytic antibodies through vaccination or direct binding and neutralization of the bacterial surface via monoclonal antibodies to facilitate immune clearance.