O-antigen of Escherichia coli serotype O2 (null)

The O-antigen of Escherichia coli serotype O2 is a strain-specific polysaccharide component of the outer membrane lipopolysaccharide (LPS) layer. It consists of repeating units of various sugar residues (in O2, mainly three L-rhamnose, N-acetylglucosamine, and N-acetyl-D-galactosamine), synthesized by a dedicated gene cluster (O-antigen gene cluster, or O-AGC)[3]. The O-antigen is highly variable among E. coli serogroups and is a key determinant for bacterial serotyping, immune evasion, and pathogenicity. It is a useful marker for strain differentiation, epidemiological studies, and is considered a potential target for diagnostic tools, monoclonal antibody therapies, and vaccine development, although major clinical products are not yet standard. In O2 strains, the O-antigen structure and biosynthetic genes may vary due to genetic recombination, leading to diversity and occasional cross-reactivity with other O-serogroups[1][3][4].

Other names

E. coli O2 O-antigenE. coli serogroup O2 O-polysaccharideO2 O-antigenO2 LPS O-antigen

Antibody-mediated neutralization: Antibodies bind the O-antigen, promoting complement activation, opsonophagocytosis, or blocking attachment to host cells. Inhibition of bacterial survival: Prevents bacterial evasion of host immune system. Vaccine-induced immune memory (if used as a vaccine antigen).