Escherichia coli O4 antigen (O4 antigen)

The Escherichia coli O4 antigen is a specific O-polysaccharide component of the lipopolysaccharide (LPS) located on the outer membrane of certain E. coli strains. It serves as a primary surface antigen and is a critical determinant for serotyping the bacteria, distinguishing it from hundreds of other O-serotypes. The O4 serotype is frequently associated with extraintestinal pathogenic E. coli (ExPEC), which are leading causes of urinary tract infections, sepsis, and neonatal meningitis in humans (Poolman et al., 2020, J Infect Dis). Biologically, the O4 antigen contributes to bacterial virulence by providing resistance against the host's innate immune system, specifically by inhibiting serum-mediated killing and phagocytosis (Raetz & Whitfield, 2002, Annu Rev Biochem). In the context of drug development, the O4 antigen is a major target for multivalent conjugate vaccines, such as Janssen's ExPEC9V, which aim to elicit protective immune responses against the most prevalent invasive E. coli strains. These vaccines work by inducing the production of O-antigen-specific antibodies that promote bacterial clearance via opsonophagocytosis (Frenck et al., 2019, Vaccine).

Other names

E. coli O4 LPSO4-specific polysaccharideO4-antigenEscherichia coli serogroup O4O4 lipopolysaccharide

Induction of opsonophagocytic antibodies and complement-mediated killing through active immunization