title: Mapping of epitopes recognized by antibodies induced by immunization of mice with PspA and PspC.
abstract: Pneumococcal surface protein A (PspA) and pneumococcal surface protein C (PspC) are important candidates for an alternative vaccine against pneumococcal infections. Since these antigens show variability, the use of variants that do not afford broad protection may lead to the selection of vaccine escape bacteria. Epitopes capable of inducing antibodies with broad cross-reactivities should thus be the preferred antigens. In this work, experiments using peptide arrays show that most linear epitopes recognized by antibodies induced in mice against different PspAs were located at the initial 44 amino acids of the mature protein and that antibodies against these linear epitopes did not confer protection against a lethal challenge. Conversely, linear epitopes recognized by antibodies to PspC included the consensus sequences involved in the interaction with human factor H and secretory immunoglobulin A (sIgA). Since linear epitopes of PspA were not protective, larger overlapping fragments containing 100 amino acids of PspA of strain Rx1 were constructed (fragments 1 to 7, numbered from the N terminus) to permit the mapping of antibodies with conformational epitopes not represented in the peptide arrays. Antibodies from mice immunized with fragments 1, 2, 4, and 5 were capable of binding onto the surface of pneumococci and mediating protection against a lethal challenge. The fact that immunization of mice with 100-amino-acid fragments located at the more conserved N-terminal region of PspA (fragments 1 and 2) induced protection against a pneumococcal challenge indicates that the induction of antibodies against conformational epitopes present at this region may be important in strategies for inducing broad protection against pneumococci.
authors.affiliation: Centro de Biotecnologia, Instituto Butantan, São Paulo, Brazil.
authors.forename: Cintia F M
authors.initials: CF
authors.lastname: Vadesilho
authors.affiliation: Respiratory Infection Group, Liverpool School of Tropical Medicine, Liverpool, United Kingdom.
authors.forename: Daniela M
authors.initials: DM
authors.lastname: Ferreira
authors.affiliation: Respiratory Infection Group, Liverpool School of Tropical Medicine, Liverpool, United Kingdom.
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Gordon
authors.affiliation: Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA.
authors.forename: David E
authors.initials: DE
authors.lastname: Briles
authors.affiliation: Centro de Biotecnologia, Instituto Butantan, São Paulo, Brazil.
authors.forename: Adriana T
authors.initials: AT
authors.lastname: Moreno
authors.affiliation: Centro de Biotecnologia, Instituto Butantan, São Paulo, Brazil.
authors.forename: Maria Leonor S
authors.initials: ML
authors.lastname: Oliveira
authors.affiliation: Centro de Biotecnologia, Instituto Butantan, São Paulo, Brazil.
authors.forename: Paulo L
authors.initials: PL
authors.lastname: Ho
authors.affiliation: Centro de Biotecnologia, Instituto Butantan, São Paulo, Brazil eliane.miyaji@butantan.gov.br.
authors.forename: Eliane N
authors.initials: EN
authors.lastname: Miyaji
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology; D000907:Antibodies, Bacterial / Q000276:immunology; D001426:Bacterial Proteins / Q000276:immunology*; D017242:Complement Factor H / Q000276:immunology; D003429:Cross Reactions / Q000276:immunology; D018604:Epitope Mapping; D000939:Epitopes / Q000276:immunology*; D005260:Female; D007114:Immunization; D007070:Immunoglobulin A / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology; D011008:Pneumococcal Infections / Q000276:immunology / Q000517:prevention & control; D022242:Pneumococcal Vaccines / Q000276:immunology*; D013296:Streptococcus pneumoniae / Q000276:immunology
chemical_list: D000906:Antibodies; D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; C493495:CFH protein, human; D000939:Epitopes; D007070:Immunoglobulin A; D010446:Peptide Fragments; D022242:Pneumococcal Vaccines; C110344:SpsA protein, Streptococcus pneumoniae; C051592:pneumococcal surface protein A; D017242:Complement Factor H