title: The role of peptide loops of the Bordetella pertussis protein P.69 pertactin in antibody recognition.
abstract: Bordetella pertussis, the etiological agent of whooping cough, is re-emerging in several countries with a traditionally high vaccine uptake. In these B. pertussis strains, polymorphisms were found in several proteins, including P.69 pertactin (P.69 Prn). P.69 Prn, an adhesin, contains two variable regions which are composed of repeats, one of which flanks the receptor binding site. Antibody titers against P.69 Prn correlate with protection and P.69 Prn is one of the components of acellular pertussis vaccines. Nevertheless, little is known about the structure and location of P.69 Prn epitopes. We used a three pronged approach to identify discontinuous epitopes that are recognized by mouse monoclonal antibodies, i.e. site-directed mutagenesis, deletion mapping and competition assays. Site-directed mutagenesis was focused on regions of P.69 Prn predicted to form loops according to the crystal structure. In this report we describe the location of several discontinuous epitopes that are also recognized by human antibodies. Our results reveal an important role of the N-terminus in immune recognition. We provide data for an indirect role of loops in immune evasion by masking of epitopes. We propose that the repeat regions have evolved to allow rapid antigenic variation to deflect the immune response from the functional domain of P.69 Prn. The results presented here provide a better understanding of the structure and function of variable loops and their role in the persistence of pathogens in immunologically primed populations.
authors.affiliation: Laboratory for Vaccine Preventable Diseases, National Institute for Public Health and the Environment, Bilthoven, The Netherlands.
authors.forename: Marcel
authors.initials: M
authors.lastname: Hijnen
authors.forename: Richarda
authors.initials: R
authors.lastname: de Voer
authors.forename: Frits R
authors.initials: FR
authors.lastname: Mooi
authors.forename: Rutger
authors.initials: R
authors.lastname: Schepp
authors.forename: Ed E
authors.initials: EE
authors.lastname: Moret
authors.forename: Pieter
authors.initials: P
authors.lastname: van Gageldonk
authors.forename: Gaby
authors.initials: G
authors.lastname: Smits
authors.forename: Guy A M
authors.initials: GA
authors.lastname: Berbers
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology; D000911:Antibodies, Monoclonal / Q000276:immunology; D000942:Antigens, Bacterial / Q000737:chemistry / Q000276:immunology*; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology*; D001886:Bordetella pertussis / Q000737:chemistry* / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D010455:Peptides / Q000737:chemistry* / Q000276:immunology; D010567:Pertussis Vaccine / Q000276:immunology*; D010566:Virulence Factors, Bordetella / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D010455:Peptides; D010567:Pertussis Vaccine; D010566:Virulence Factors, Bordetella; C068929:pertactin