Circumscribing the conformational peptide epitope landscape.

The development of vaccines for new and re-emerging pathologies and infections is based on the ability to define immunogenic epitopes. An immunogenic B-cell peptide epitope is a specific restricted antigen region that is capable of eliciting a humoral immune response and of combining with a specific site on antibodies. Using a number of experimental models and based on data from several literature reports, we identified low levels of sequence similarity to the host proteome as one of the main factors modulating the B-cell epitope repertoire in the humoral immune response. In point of fact, a low level of sequence identity to the host proteins is a common denominator unifying the composite, disparate assembly of linear peptide B-cell epitopes that has been experimentally validated and described in the literature. Here, we explore the proteomic similarity of conformational epitopes experimentally validated and described in published reports. Again, discontinuous epitopic structures formed by non-contiguous amino acid residues were found to define peptide sequences with a low level of similarity to the host. The present meta-analysis adds further significance to the immunological low-similarity theory and its clinical implications. Potentially, low-similarity peptide epitopes pave the way for novel effective vaccines in cancer, autoimmunity, and infectious diseases.