Selection of mimotopes of Bovine Viral Diarrhoea Virus using a solid-phase peptide library

Peptide mimics of hapten DNP: the effect of affinity of anti-DNP monoclonal antibodies for the selection of phage-displayed mimotopes

Biopanning of two linear (6- and 15-mer) and two constrained (10- and 17-mer) phage-displayed peptide libraries with two anti-DNP monoclonal antibodies (mAbs) selected seven unique peptide sequences using only the low affinity anti-DNP monoclonal antibody. The selected peptides contained two of 6, one of 10, two of 15 and two of 17 amino acids in length. They were all rich in hydrophobic residues. Both 15-mer peptides had antigenic regions of eight amino acids as revealed by a spot scan assay. Two of the 17-mer and one of the 10-mer peptides displayed on phage competed with free DNP for the low affinity anti-DNP mAb. These findings highlight (i) the selective power of phage displayed peptide libraries to identify peptides that mimic the shape of a small hapten molecule such as DNP, (ii) the possible preferential bias of phage libraries towards low affinity antibodies, (iii) the importance of using a panel of phage libraries for selecting peptide mimics.

Unravelling autoimmune pathogenesis by screening random peptide libraries with human sera

The incidence of autoimmunity is increasing worldwide. The long preclinical period of autoimmune disorders is characterised by an enhanced exposure over time of autoreactive T cells to an increased number of autoantigenic determinants and autoantibodies production. The discovery of novel autoimmune-disease related epitopes is a task that remains extremely challenging in order to establish predictive and preventive strategies of the disease onset. In this Opinion article we highlight the contribution of screening combinatorial random peptide libraries with patients sera in unravelling the etiopathogenesis of autoimmunity.

A novel peptide mimotope identified as a potential immunosuppressive vaccine for organ transplantation

We reported that anti-histone H1 autoantibody is one of the main immunosuppressive factors in serum that is induced after orthotopic liver transplantation in a rat tolerogenic model. We generated a novel anti-histone H1 IgM mAb produced by hybridoma 16G9 (16G9 mAb) that shows MLR-inhibitory activity. Identification of a functional epitope responsible for the immunosuppressive activity of 16G9 mAb may lead to the establishment of a novel therapeutic strategy. We used a combinatorial phage display peptide library to screen for peptides that bind to 16G9 mAb. Consequently, two peptides that bind to 16G9 mAb, SSV and LPQ, were selected from the library. The binding of 16G9 mAb to histone H1 was inhibited by SSV. SSV was recognized by rat tolerogenic post-orthotopic liver transplantation serum and the binding to SSV was inhibited by histone H1. Mice were immunized with keyhole limpet hemocyanin-conjugated SSV and LPQ. Abs induced by SSV immunization inhibited Con A-stimulated splenocyte proliferation, and the inhibition was neutralized by preincubation with SSV. Splenocytes stimulated by anti-CD3 Ab were inhibited by SSV-induced Abs using CFSE labeling. SSV immunization in rats before heterotopic heart transplantation resulted in significant prolonged allograft survival. These findings suggested that SSV is a functional histone H1-binding epitope for 16G9 mAb. SSV is capable of determining serum immunoreactivity against histone H1 as an index marker for tolerance. The inhibitory activity of SSV-induced Abs on blast cell proliferation and the prolonged graft survival that results from SSV immunization imply a potential for the development of an immunosuppressive vaccine.