Escherichia coli O1a O-antigen polysaccharide epitope (E. coli O1a O-antigen)

The Escherichia coli O1a O-antigen is a specific polysaccharide epitope located on the outer membrane of certain E. coli strains, particularly those classified as extraintestinal pathogenic E. coli (ExPEC) (Poolman & Wacker, 2016). As the most distal component of the lipopolysaccharide (LPS) molecule, the O-antigen is highly immunogenic and serves as a primary target for the host's immune system (DebRoy et al., 2016). In the context of infection, the O1a O-antigen plays a vital role in bacterial survival by providing resistance against serum-mediated killing and preventing phagocytosis by host immune cells (Miajlovic & Smith, 2014). Because of its critical role in pathogenesis and its accessibility on the bacterial surface, the O1a O-antigen is a key component in the development of multivalent glycoconjugate vaccines, such as Janssen's ExPEC9V and ExPEC10V (ClinicalTrials.gov, NCT04899336). These vaccines are designed to induce opsonophagocytic antibodies that target the O-antigen, thereby facilitating the clearance of the bacteria and preventing invasive diseases like urosepsis and bacteremia (Kowarik et al., 2013). The O1a serotype is specifically included in these formulations due to its prevalence in clinical isolates from patients with severe E. coli infections (Frenck et al., 2019).

Other names

O1a antigenEscherichia coli serogroup O1a polysaccharideE. coli O1a LPSO1a polysaccharide epitope

Induction of opsonophagocytic antibodies through active immunization