title: Characterisation and protective capacity of monoclonal antibodies elicited in mice against protein epitopes of antibiotic-exposed Escherichia coli.
abstract: The binding capacity and the protective activity of three monoclonal antibodies (MAbs)-ARM 1-4, ARM 1-7 and ARM 2-2-obtained from spleen cells of mice immunised with Escherichia coli O6:K-pre-treated with sub-MIC of aztreonam were studied. The MAbs belonged to IgG1 isotype and showed different reactivity toward protein epitopes of E. coli in an immunoblotting assay. ARM 1-4 recognised epitopes on molecules of 30 kDa and 40 kDa. ARM 1-7 identified an epitope of a molecule of 41 kDa, and ARM 2-2 recognised epitopes of molecules of 15 kDa and 41 kDa. In ELISA the MAbs cross-reacted with E. coli O7:K-, E. coli O111:B4 and E. coli O128:K- with different binding affinity. Furthermore, the MAbs showed complement-dependent bactericidal activity. The MAbs displayed different protective capacities when given to mice 90 min before lethal challenges with 2 x LD50, 4 x LD50 and 8 x LD50 of E. coli strains. In all but one instance (ARM 1-4 versus E. coli O7:K-) it was not possible to correlate protective capacity with binding affinity of a MAb to a given bacterial cell. Therefore, the epitopes recognised by the MAb may be more closely associated with bacterial virulence than in binding to the bacterial cell.
authors.affiliation: Institute of Microbiology, University of Rome La Sapienza, Italy.
authors.forename: M T
authors.initials: MT
authors.lastname: Lun
authors.forename: G
authors.initials: G
authors.lastname: Raponi
authors.forename: A M
authors.initials: AM
authors.lastname: Amatucci
authors.forename: P G
authors.initials: PG
authors.lastname: Natali
authors.forename: R
authors.initials: R
authors.lastname: Fraioli
authors.forename: C
authors.initials: C
authors.lastname: Mancini
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis / Q000276:immunology; D000911:Antibodies, Monoclonal / Q000096:biosynthesis / Q000276:immunology*; D000918:Antibody Specificity; D000942:Antigens, Bacterial / Q000276:immunology*; D001398:Aztreonam / Q000494:pharmacology; D003165:Complement System Proteins / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology; D004926:Escherichia coli / Q000187:drug effects / Q000276:immunology*; D004927:Escherichia coli Infections / Q000517:prevention & control*; D005260:Female; D006825:Hybridomas; D007114:Immunization; D015151:Immunoblotting; D007074:Immunoglobulin G / Q000096:biosynthesis / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008997:Monobactams / Q000494:pharmacology
chemical_list: D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D000942:Antigens, Bacterial; D000939:Epitopes; D007074:Immunoglobulin G; D008997:Monobactams; D003165:Complement System Proteins; D001398:Aztreonam