Escherichia coli O157:H7 O-antigen (O157 O-antigen)

The Escherichia coli O157:H7 O-antigen is a complex polysaccharide component of the outer membrane lipopolysaccharide (LPS) that defines the O157 serotype of enterohemorrhagic E. coli (EHEC) [1, 5]. It consists of repeating tetrasaccharide units containing N-acetyl-D-perosamine, L-fucose, D-glucose, and N-acetyl-D-galactose [2, 11]. Biologically, the O-antigen is essential for maintaining bacterial cell wall integrity and protecting the organism from host immune defenses, such as the complement system and antimicrobial peptides [4, 10]. It also plays a significant role in the colonization of the host's intestinal mucosa [5, 13]. In the context of disease, E. coli O157:H7 is a major foodborne pathogen responsible for hemorrhagic colitis and the life-threatening hemolytic uremic syndrome (HUS), primarily through the production of Shiga toxins [1, 16]. As a primary surface-exposed molecule, the O157 O-antigen is a key therapeutic target for the development of glycoconjugate vaccines and monoclonal antibodies [6, 9]. Investigational vaccines, such as O157-rEPA, aim to induce bactericidal antibodies that neutralize the bacteria and prevent colonization [6, 11]. Monoclonal antibodies targeting the O-antigen are also being explored for passive immunization to provide immediate protection during outbreaks [6, 8]. A major therapeutic challenge is the risk of Shiga toxin release if the bacteria are lysed, which is a known complication of traditional antibiotic treatment; therefore, O-antigen-targeted therapies focus on neutralization and clearance without triggering mass lysis [8, 16].

Other names

O157-specific polysaccharideO157 somatic antigenE. coli O157 lipopolysaccharideO157 OSP

Induction of bactericidal antibodies, opsonization, and neutralization of bacterial attachment to prevent intestinal colonization [6, 7, 11].