title: Plasmodium vivax promiscuous T-helper epitopes defined and evaluated as linear peptide chimera immunogens.
abstract: Clinical trials of malaria vaccines have confirmed that parasite-derived T-cell epitopes are required to elicit consistent and long-lasting immune responses. We report here the identification and functional characterization of six T-cell epitopes that are present in the merozoite surface protein-1 of Plasmodium vivax (PvMSP-1) and bind promiscuously to four different HLA-DRB1* alleles. Each of these peptides induced lymphoproliferative responses in cells from individuals with previous P. vivax infections. Furthermore, linear-peptide chimeras containing the promiscuous PvMSP-1 T-cell epitopes, synthesized in tandem with the Plasmodium falciparum immunodominant circumsporozoite protein (CSP) B-cell epitope, induced high specific antibody titers, cytokine production, long-lasting immune responses, and immunoglobulin G isotype class switching in BALB/c mice. A linear-peptide chimera containing an allele-restricted P. falciparum T-cell epitope with the CSP B-cell epitope was not effective. Two out of the six promiscuous T-cell epitopes exhibiting the highest anti-peptide response also contain B-cell epitopes. Antisera generated against these B-cell epitopes recognize P. vivax merozoites in immunofluorescence assays. Importantly, the anti-peptide antibodies generated to the CSP B-cell epitope inhibited the invasion of P. falciparum sporozoites into human hepatocytes. These data and the simplicity of design of the chimeric constructs highlight the potential of multimeric, multistage, and multispecies linear-peptide chimeras containing parasite promiscuous T-cell epitopes for malaria vaccine development.
authors.affiliation: Fundación Instituto de Inmunología de Colombia (FIDIC), Santafé de Bogotá, Colombia.
authors.forename: Ivette
authors.initials: I
authors.lastname: Caro-Aguilar
authors.forename: Alexandra
authors.initials: A
authors.lastname: Rodríguez
authors.forename: J Mauricio
authors.initials: JM
authors.lastname: Calvo-Calle
authors.forename: Fanny
authors.initials: F
authors.lastname: Guzmán
authors.forename: Patricia
authors.initials: P
authors.lastname: De la Vega
authors.forename: Manuel Elkin
authors.initials: ME
authors.lastname: Patarroyo
authors.forename: Mary R
authors.initials: MR
authors.lastname: Galinski
authors.forename: Alberto
authors.initials: A
authors.lastname: Moreno
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000913:Antibodies, Protozoan / Q000276:immunology; D018604:Epitope Mapping; D018985:Epitopes, B-Lymphocyte / Q000276:immunology; D018984:Epitopes, T-Lymphocyte / Q000276:immunology*; D005260:Female; D006684:HLA-DR Antigens / Q000276:immunology*; D059811:HLA-DRB1 Chains; D006801:Humans; D020066:Merozoite Surface Protein 1 / Q000138:chemical synthesis / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010455:Peptides / Q000235:genetics / Q000276:immunology; D010963:Plasmodium falciparum / Q000276:immunology; D010966:Plasmodium vivax / Q000276:immunology*; D015800:Protozoan Proteins / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
chemical_list: D000913:Antibodies, Protozoan; D018985:Epitopes, B-Lymphocyte; D018984:Epitopes, T-Lymphocyte; D006684:HLA-DR Antigens; D059811:HLA-DRB1 Chains; D020066:Merozoite Surface Protein 1; D010455:Peptides; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; C041595:circumsporozoite protein, Protozoan