Phage displayed peptides and anti-idiotype antibodies recognised by a monoclonal antibody directed against a diagnostic antigen of Mycoplasma capricolum subsp capripneumoniae

A monoclonal antibody (Mab 4.52) raised against Mycoplasma capricolum subsp . capripneumoniae (Mccp) cell lysate was used as a template to obtain subst itute antigens recognised by its paratope. Two approaches were investigated : a 17-mer random peptide library displayed on the surface of a filamentous phage was screened by panning on the immobilised Mab 4.52 and antiidiotype antibodies were generated by immunising a chicken with the F(ab ')(2) frag ments of the antibody. Analysis of the peptide sequences displayed by the i solated phages identified two peptides. Both contained two cysteine residue s and had identical or similar amino acids in positions 5 (P), 8 (I/L) and 13 (L). The fusion phages were also recognised by Mab 4.52 in enzyme-linked immunosorbent assay (ELISA) and binding was shown by surface plasmon reson ance. One of the peptides was a markedly better inhibitor (67%) of the bind ing of Mab 4.52 to its original antigen than the other (20%) at 1 mg/ml. Af ter absorption, to remove isotypic and allotypic reactivities, the anti-idi otype IgY was specifically recognised by Mab 4.52 in ELISA and was able to inhibit its binding to the original antigen, whereas anti-idiotype antibodi es raised against a bluetongue virus-specific antibody had no effect.. In s pite of unequivocal binding of the anti-idiotype antibodies and the fusion phages to the paratope of Mab 4.52, goat antisera appeared not to react wit h either of the surrogate antigens. In contrast, the test sera bound to the original antigen suggesting that Mab 4.52 does not recognise exactly the s ame antigenic site as antibodies in the goat antisera. (C) 2001 Elsevier Sc ience B.V. All rights reserved.