title: Defining species-specific immunodominant B cell epitopes for molecular serology of Chlamydia species.
abstract: Urgently needed species-specific enzyme-linked immunosorbent assays (ELISAs) for the detection of antibodies against Chlamydia spp. have been elusive due to high cross-reactivity of chlamydial antigens. To identify Chlamydia species-specific B cell epitopes for such assays, we ranked the potential epitopes of immunodominant chlamydial proteins that are polymorphic among all Chlamydia species. High-scoring peptides were synthesized with N-terminal biotin, followed by a serine-glycine-serine-glycine spacer, immobilized onto streptavidin-coated microtiter plates, and tested with mono-specific mouse hyperimmune sera against each Chlamydia species in chemiluminescent ELISAs. For each of nine Chlamydia species, three to nine dominant polymorphic B cell epitope regions were identified on OmpA, CT618, PmpD, IncA, CT529, CT442, IncG, Omp2, TarP, and IncE proteins. Peptides corresponding to 16- to 40-amino-acid species-specific sequences of these epitopes reacted highly and with absolute specificity with homologous, but not heterologous, Chlamydia monospecies-specific sera. Host-independent reactivity of such epitopes was confirmed by testing of six C. pecorum-specific peptides from five proteins with C. pecorum-reactive sera from cattle, the natural host of C. pecorum. The probability of cross-reactivity of peptide antigens from closely related chlamydial species or strains correlated with percent sequence identity and declined to zero at <50% sequence identity. Thus, phylograms of B cell epitope regions predict the specificity of peptide antigens for rational use in the genus-, species-, or serovar-specific molecular serology of Chlamydia spp. We anticipate that these peptide antigens will improve chlamydial serology by providing easily accessible assays to nonspecialist laboratories. Our approach also lends itself to the identification of relevant epitopes of other microbial pathogens.
authors.affiliation: Department of Pathobiology, Auburn University, Auburn, Alabama, USA.
authors.forename: K Shamsur
authors.initials: KS
authors.lastname: Rahman
authors.affiliation: Department of Pathobiology, Auburn University, Auburn, Alabama, USA.
authors.forename: Erfan U
authors.initials: EU
authors.lastname: Chowdhury
authors.affiliation: Department of Pathobiology, Auburn University, Auburn, Alabama, USA.
authors.forename: Anil
authors.initials: A
authors.lastname: Poudel
authors.affiliation: Friedrich-Loeffler-Institut (Federal Research Institute for Animal Health), Jena, Germany.
authors.forename: Anke
authors.initials: A
authors.lastname: Ruettger
authors.affiliation: Friedrich-Loeffler-Institut (Federal Research Institute for Animal Health), Jena, Germany.
authors.forename: Konrad
authors.initials: K
authors.lastname: Sachse
authors.affiliation: Department of Pathobiology, Auburn University, Auburn, Alabama, USA kaltebe@auburn.edu.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Kaltenboeck
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology*; D000942:Antigens, Bacterial / Q000276:immunology*; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000276:immunology*; D001426:Bacterial Proteins / Q000276:immunology; D002417:Cattle; D002689:Chlamydia / Q000737:chemistry* / Q000145:classification / Q000235:genetics / Q000276:immunology*; D002690:Chlamydia Infections / Q000276:immunology; D003429:Cross Reactions; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D018985:Epitopes, B-Lymphocyte / Q000737:chemistry / Q000276:immunology*; D016056:Immunodominant Epitopes / Q000737:chemistry / Q000276:immunology*; D051379:Mice; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology; D010802:Phylogeny; D016415:Sequence Alignment; D013045:Species Specificity
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D018985:Epitopes, B-Lymphocyte; D016056:Immunodominant Epitopes; D010446:Peptide Fragments