title: Characterization of Escherichia coli K1 colominic acid-specific murine antibodies that are cross-protective against Neisseria meningitidis groups B, C, and Y.
abstract: The capsular polysaccharide (PS) of Neisseria meningitidis serogroup B (NMGB) is α(2-8)-linked N-acetylneuraminic acid (Neu5Ac), which is almost identical to the O-acetylated colominic acid (CA) of Escherichia coli K1 Although E. coli K1 has long been known to elicit cross-protective antibodies against NMGB, limited information on these highly cross-reactive antibodies is available. In the present study, six new monoclonal antibodies (mAbs) specific to both E. coli K1 CA and NMGB PS were produced by immunizing Balb/c mice with E. coli K1, and their serological and molecular properties were characterized, together with 12 previously reported hybridoma mAbs. Among the bactericidal mAbs against NMGB, both HmenB5 and HmenB18, which are genetically identical though of different mouse origins, were able to kill serogroup C and Y meningococci. Based on SPR sensograms, the binding affinity of HmenB18 for PS was suggested to be associated with at least two different binding forces: the polyanionicity of Neu5Ac and an interaction with the O-acetyl groups of Neu5Ac. Molecular analysis showed that similar to most mAbs presenting a few restricted V region germline genes, the V region genes of HmenB18 were 979% and 986% identical to the closest IGHV1-1401 and IGLV15-10301 germline gene alleles, respectively, and V-D-J editing in this mAb generated an unusually long VH-CDR3 sequence (17 amino acid residues), containing one basic arginine, two hydrophobic isoleucine residues and a 'YAMDY' motif. Models of the mAb combining sites demonstrate that most of the mAbs exhibited a wide, shallow groove with a high overall positive charge, as seen in mAb735, which is specific for a polyanionic helical epitope. In contrast, the combining site of HmenB18 was shown to be wide but to present a relatively weak positive charge, consistent with the extensive recognition by HmenB18 of the various structural epitopes formed with the Neu5Ac residue and its O-acetylation.
authors.affiliation: Ewha Center for Vaccine Evaluation and Study, Medical Research Institute, School of Medicine, Ewha Womans University, Seoul 158-710, Republic of Korea.
authors.forename: In Ho
authors.initials: IH
authors.lastname: Park
authors.affiliation: Department of Pathology, School of Medicine, Division of Laboratory Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, United States.
authors.forename: Jisheng
authors.initials: J
authors.lastname: Lin
authors.affiliation: Department of Pediatrics, Seoul National University Boramae Hospital, Seoul National University College of Medicine, Seoul 156-707, Republic of Korea.
authors.forename: Ji Eun
authors.initials: JE
authors.lastname: Choi
authors.affiliation: Department of Microbiology, Yonsei University College of Medicine, Seoul 120-752, Republic of Korea; Severance Biomedical Science Institute and Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, Seoul 120-752, Republic of Korea. Electronic address: jsshin6203@yuhs.ac.
authors.forename: Jeon-Soo
authors.initials: JS
authors.lastname: Shin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology*; D000911:Antibodies, Monoclonal / Q000235:genetics / Q000276:immunology; D000915:Antibody Affinity / Q000276:immunology; D000918:Antibody Specificity / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology; D016667:Bacterial Capsules / Q000276:immunology*; D001483:Base Sequence; D002460:Cell Line; D056738:Cross Protection / Q000276:immunology; D004926:Escherichia coli / Q000276:immunology*; D006825:Hybridomas; D007135:Immunoglobulin Variable Region / Q000235:genetics / Q000276:immunology; D008585:Meningitis, Meningococcal / Q000517:prevention & control*; D051379:Mice; D008807:Mice, Inbred BALB C; D038541:Neisseria meningitidis, Serogroup B / Q000276:immunology*; D038542:Neisseria meningitidis, Serogroup C / Q000276:immunology*; D038581:Neisseria meningitidis, Serogroup Y / Q000276:immunology*; D011134:Polysaccharides / Q000276:immunology*; D011135:Polysaccharides, Bacterial; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D020349:Surface Plasmon Resonance
chemical_list: D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D000942:Antigens, Bacterial; D007135:Immunoglobulin Variable Region; D011134:Polysaccharides; D011135:Polysaccharides, Bacterial; C036962:capsular polysaccharide K1; C014420:colominic acid
keywords: Capsular polysaccharide; N-acetylneuraminic acid; Neisseria meningitidis, Escherichia coli K1; O-acetylation, Monoclonal antibody; Structure modeling; Variable germline gene