Escherichia coli O15 antigen (O15)

The Escherichia coli O15 antigen is a specific O-polysaccharide component of the lipopolysaccharide (LPS) found on the outer membrane of E. coli strains belonging to the O15 serogroup [1, 5]. As a key surface-exposed molecule, it plays a critical role in the bacterium's survival by providing a physical barrier against environmental stressors and protecting the pathogen from the host's innate immune system, particularly complement-mediated lysis [5, 7]. E. coli O15 is frequently associated with extraintestinal pathogenic E. coli (ExPEC) infections, including urinary tract infections (UTIs) and invasive bacteremia [1, 2]. Due to its high prevalence in clinical isolates and its accessibility on the bacterial surface, the O15 antigen is a primary target for the development of multivalent conjugate vaccines, such as ExPEC9V and ExPEC10V [1, 3, 6]. These vaccines aim to elicit opsonophagocytic antibodies that promote the clearance of the bacteria by the host's immune cells, thereby preventing severe systemic infections [3, 6]. The O15 antigen is synthesized by a specific gene cluster, including the wzx flippase and wzy polymerase genes, which are used as biomarkers for serotype identification [7, 11]. Targeting this antigen provides a serotype-specific approach to preventing infections caused by one of the most common causes of sepsis in older adults [1, 2].

Other names

E. coli O15 O-antigen [1, 5]O15 lipopolysaccharide [3, 5]O15-polysaccharide [1, 6]ECOO15 [2]O15 antigen [7, 11]

Induction of opsonophagocytic antibodies against the O15 antigen to facilitate bacterial clearance by the host immune system [3, 6].