Fine mapping of a foot-and-mouth disease virus epitope recognized by serotype-independent monoclonal antibody 4B2

VP2 is a structural protein of the foot-and-mouth disease virus (FMDV). In this study, a FMDV serotype-in-dependent monoclonal antibody (MAb), 4B2, was generated. By screening a phage-displayed random 12-peptide library, we found positive phages displaying the consensus motif ETTXLE (X is any amino acid (aa)), which is highly homologous to ⁶ETTLLE¹¹ at the N-terminus of the VP2 protein. Subsequently, a series of GST-fusion proteins expressing a truncated N-terminus of VP2 were examined by western blot analysis using the MAb 4B2. The results indicated that the motif ⁶ETTLLE¹¹ of VP2 may be the minimal requirement of the epitope recognized by 4B2. Moreover, a 12-aa peptide ²KKTEETTLLEDR¹³ was shown to be the minimal unit of the epitope with maximal binding activity to 4B2. Alanine-scanning analysis demonstrated thatThr⁷, Thr⁸, and Leu¹⁰ are the functional residues of the 4B2 epitope Glu⁶ and Leu⁹ are required residues, and Glu¹¹ plays a crucial role in the binding of MAb 4B2. The fine mapping of the epitope indicated that MAb 4B2 has the potential to be used in FMDV diagnosis.