The cloning of the single-chain variable fragment antibody (scFv) was performed as described previously by our group. Three-dimensional structure predictions for scFv were generated using the Model Antibody of Discovery Studio from BIOVIA Co., Ltd. (San Diego, CA, USA) based on the primary structure of mAbs. After loading the amino sequences, the framework templates for the variable fragment (Fv) of the antibody sequence were identified for homology modeling. According to the sequence similarity and identity, the best matching overall templates were used to model the antibody framework for the antibodies, which determined the relative spatial orientations of the light and heavy chains. The binding between antibosies and epitopes (MEL or NIA) was performed with the CDOCKER docking program of Discovery Studio. After docking the epitopes into the top-ranked cavity of the antibody, the binding position of each complex with the highest score was selected to provide a starting orientation of each antibody-epitope moiety. Rosetta protein-protein docking protocol was then used for the antibody-antibody docking calculations to provide the relative positions of both antibodies. The antibody-epitope complex was then superimposed onto each antibody in the antibody-antibody complex, and a shared binding cavity was formed between the two antibodies. The model analytes MN1-MN9