Escherichia coli O1 antigen (O1 antigen)

The Escherichia coli O1 antigen is the distal polysaccharide component of the lipopolysaccharide (LPS) found on the outer membrane of E. coli strains belonging to the O1 serogroup (Stenutz et al., 2006). It serves as a critical structural element and a primary interface between the bacterium and the host immune system, playing a significant role in protecting the pathogen from complement-mediated lysis and phagocytosis (Poolman & Wacker, 2016). As a major surface-exposed molecule, the O1 antigen is a key determinant of serological specificity and a primary target for the development of glycoconjugate vaccines and monoclonal antibodies aimed at preventing extra-intestinal pathogenic E. coli (ExPEC) infections (Huttner et al., 2017). These infections include urinary tract infections, bacteremia, and neonatal meningitis, where O1 is one of the most frequently isolated serotypes. Therapeutic strategies typically involve the use of O1-polysaccharide conjugated to carrier proteins to elicit high-titer, opsonophagocytic antibodies that enhance bacterial clearance (Janssen, 2023). The structural integrity of the O1 antigen is essential for bacterial survival in the host bloodstream, making it an attractive target for neutralizing therapies. Current vaccine candidates, such as ExPEC9V, include the O1 antigen to provide broad protection against the most prevalent invasive E. coli strains. Challenges in targeting this molecule include the high degree of antigenic variation among E. coli serotypes, which requires multi-valent approaches to achieve sufficient clinical coverage.

Other names

E. coli O1 LPSO1-specific polysaccharideO-antigen 1Escherichia coli O1 lipopolysaccharide

Induction of opsonophagocytic antibodies through active immunization with polysaccharide-protein conjugates (Poolman & Wacker, 2016).