Molecular localization and crossreactivity of two epitopes of noxiustoxin from scorpion Centruroides noxius, identified by a panel of monoclonal antibodies and peptide mimotopes

Mimotopes derived from peptide phage display libraries may reproduce basic functions of epitopes including their antigenicity. In case of toxins, this property makes phage displayed mimotopes highly specific vaccine components free of the toxicity. To explore the potential of mimotopes for vaccine development, their ability of substituting the whole toxin molecule deserves a detailed characterization. We used mimotopes of noxiustoxin (NTX), a neurotoxin from scorpion Centruroides noxius, for studying its epitopes recognized by a panel of six monoclonal antibodies (mAbs), as well as their crossreactivity with homologous toxins from other species of the Centruroides genus. Although competitive (displacement) immunoassay showed that all six mAbs inhibit each other for binding to whole NTX molecule, the mimotopes used as specific probes allowed separation of the mAbs into two functional groups recognizing distinct non-overlapping epitopes mapped on the opposite sites of the three-dimensional structure of the toxin. The use of mimotopes permitted a precise specificity analysis of a panel of antibodies raised against this toxin, that may be very important for immunological characterization of other scorpion toxins and for vaccine development.