Escherichia coli O6 antigen (O6 antigen)

The Escherichia coli O6 antigen is a specific O-polysaccharide component of the lipopolysaccharide (LPS) located on the outer membrane of certain E. coli strains. It is a major virulence factor for extraintestinal pathogenic E. coli (ExPEC), which are frequently associated with urinary tract infections (UTIs) and life-threatening urosepsis (PMID: 29158414). The O6 antigen functions as a protective barrier that helps the bacteria evade the host's innate immune system by conferring resistance to serum-mediated killing and reducing phagocytosis (PMID: 26391411). Because it is highly immunogenic and surface-exposed, it is a primary target for the development of multivalent glycoconjugate vaccines, such as the 9-valent ExPEC9V vaccine (NCT04899336). These therapeutic strategies aim to elicit serotype-specific antibodies that facilitate the clearance of the bacteria by the host immune system through opsonophagocytosis. The O6 serotype is one of the most prevalent among clinical isolates globally, making it a high-priority target for preventative and therapeutic interventions (PMID: 32814614).

Other names

E. coli O6 O-antigenO6 lipopolysaccharideO6-LPSO6-polysaccharideO6-specific polysaccharide

Induction of opsonophagocytic antibodies and complement-mediated killing through active immunization (vaccines) or passive antibody transfer (monoclonal antibodies).