title: Orientation of epitopes influences the immunogenicity of synthetic peptide dimers.
abstract: The immunogenicity of synthetic peptide dimers based on epitope sequences derived from the mycobacterial 65-kDa antigen and the foot and mouth disease virus (FMDV) VP1 protein was examined in inbred mice. The analysis was directed towards the potential helper role of a T cell stimulatory mycobacterial epitope (65-85) with respect to poorly immunogenic sites either from the same molecule (422-436) or from VP1 (141-160). The 65-85 repeat homodimer induced an antibody response in CBA/ca but not in C57BL/6 mice, both nonresponders to the 65-85 monomer, and amplified the antibody response in BALB/c, monomer-responder mice. Analysis of the immunogenicity of hybrid dimers in BALB/c mice showed that the orientation of peptides within the dimer is critical for the extent of the produced antibody response. Only the 422-436/65-85 but not the 65-85/422-436 induced antibodies binding to the 422-436 sequence which was nonimmunogenic when injected either as a monomer or dimer. Despite the striking difference in immunogenicity, both tested hybrid dimers reacted equally in the solid-phase immunoassay with antisera raised to 65-85-dimer or 422-436/65-85 peptides or with a monoclonal antibody to the 422-436 epitope. The described differences in antibody responsiveness also cannot be attributed merely to the extent of T cell stimulation since the proliferative responses were uniformly expressed for all relevant combinations of peptides. Antisera to 65-85 dimer and 422-436/65-85 hybrid also reacted with the native 65-kDa protein. Furthermore, the production of FMDV-neutralizing antibodies in response to the 141-160 (VP1-derived)/65-85 hybrid peptide in 141-160 nonresponder B10.D2 mice also confirmed the helper activity of the 65-85 epitope. Thus, combining heterologous peptides with the N-terminal of the mycobacterial 65-85 sequence may be generally applicable for the potentiation of peptide vaccines.
authors: MRC Tuberculosis and Related Infections Unit, Royal Postgraduate Medical School, Hammersmith Hospital, London.
authors: J H
authors: JH
authors: Cox
authors: J
authors: J
authors: Ivanyi
authors: D B
authors: DB
authors: Young
authors: J R
authors: JR
authors: Lamb
authors: A D
authors: AD
authors: Syred
authors: M J
authors: MJ
authors: Francis
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology; D000914:Antibodies, Viral / Q000276:immunology; D005537:Aphthovirus / Q000276:immunology; D001426:Bacterial Proteins / Q000276:immunology* / Q000648:ultrastructure; D000939:Epitopes; D066298:In Vitro Techniques; D008213:Lymphocyte Activation; D046911:Macromolecular Substances; D051379:Mice; D009161:Mycobacterium / Q000276:immunology*; D009500:Neutralization Tests; D010455:Peptides / Q000138:chemical synthesis / Q000276:immunology*; D011487:Protein Conformation; D013154:Spleen / Q000276:immunology; D014764:Viral Proteins / Q000276:immunology* / Q000648:ultrastructure
chemical_list: D000907:Antibodies, Bacterial; D000914:Antibodies, Viral; D001426:Bacterial Proteins; D000939:Epitopes; D046911:Macromolecular Substances; D010455:Peptides; D014764:Viral Proteins