title: Two cross-reactive monoclonal antibodies recognize overlapping epitopes on Neisseria meningitidis factor H binding protein but have different functional properties.
abstract: Factor H binding protein (fHbp) is one of the main antigens of the 4-component meningococcus B (4CMenB) multicomponent vaccine against disease caused by serogroup B Neisseria meningitidis (MenB). fHbp binds the complement down-regulating protein human factor H (hfH), thus resulting in immune evasion. fHbp exists in 3 variant groups with limited cross-protective responses. Previous studies have described the generation of monoclonal antibodies (mAbs) targeting variant-specific regions of fHbp. Here we report for the first time the functional characterization of two mAbs that recognize a wide panel of fHbp variants and subvariants on the MenB surface and that are able to inhibit fHbp binding to hfH. The antigenic regions targeted by the two mAbs were accurately mapped by hydrogen-deuterium exchange mass spectrometry (HDX-MS), revealing partially overlapping epitopes on the N terminus of fHbp. Furthermore, while none of the mAbs had bactericidal activity on its own, a synergistic effect was observed for each of them when tested by the human complement serum bactericidal activity (hSBA) assay in combination with a second nonbactericidal mAb. The bases underlying fHbp variant cross-reactivity, as well as inhibition of hfH binding and cooperativity effect observed for the two mAbs, are discussed in light of the mapped epitopes.
authors.affiliation: 1Research Center, Novartis Vaccines and Diagnostics Srl, Via Fiorentina 1, 53100 Siena, Italy. vega.masignani@novartis.com.
authors.forename: Agnese
authors.initials: A
authors.lastname: Faleri
authors.forename: Laura
authors.initials: L
authors.lastname: Santini
authors.forename: Sébastien
authors.initials: S
authors.lastname: Brier
authors.forename: Werner
authors.initials: W
authors.lastname: Pansegrau
authors.forename: Paola
authors.initials: P
authors.lastname: Lo Surdo
authors.forename: Maria
authors.initials: M
authors.lastname: Scarselli
authors.forename: Francesca
authors.initials: F
authors.lastname: Buricchi
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Volpini
authors.forename: Alessia
authors.initials: A
authors.lastname: Genovese
authors.forename: Stijn
authors.initials: S
authors.lastname: van der Veen
authors.forename: Susan
authors.initials: S
authors.lastname: Lea
authors.forename: Christoph M
authors.initials: CM
authors.lastname: Tang
authors.forename: Silvana
authors.initials: S
authors.lastname: Savino
authors.forename: Mariagrazia
authors.initials: M
authors.lastname: Pizza
authors.forename: Oretta
authors.initials: O
authors.lastname: Finco
authors.forename: Nathalie
authors.initials: N
authors.lastname: Norais
authors.forename: Vega
authors.initials: V
authors.lastname: Masignani
mesh_terms: D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000276:immunology*; D000942:Antigens, Bacterial / Q000235:genetics / Q000276:immunology*; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology*; D017242:Complement Factor H / Q000276:immunology; D003429:Cross Reactions / Q000276:immunology*; D041961:Deuterium Exchange Measurement; D018604:Epitope Mapping / Q000379:methods; D000939:Epitopes / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D014644:Genetic Variation; D006801:Humans; D013058:Mass Spectrometry; D008589:Meningococcal Infections / Q000276:immunology / Q000382:microbiology; D022401:Meningococcal Vaccines / Q000276:immunology; D008958:Models, Molecular; D038541:Neisseria meningitidis, Serogroup B / Q000235:genetics / Q000276:immunology* / Q000502:physiology; D011485:Protein Binding / Q000276:immunology; D011487:Protein Conformation; D020349:Surface Plasmon Resonance
chemical_list: D000911:Antibodies, Monoclonal; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C493495:CFH protein, human; D000939:Epitopes; D022401:Meningococcal Vaccines; C484699:factor H-binding protein, Neisseria meningitidis; D017242:Complement Factor H
keywords: MenB vaccine; hydrogen/deuterium exchange mass spectrometry; mAb synergy; meningococcal antigen