Epitope mapping is often an important component ofmAb characterization.Linear (continuous) epitopes can be readily identified by probing solid-phase arrays of overlapping peptides.However, many epitopes are conformational (discontinuous) and are often difficult to investigate as the need for maintaining the native conformation frequently renders traditional strategies that rely on fragmentation followed by fragment characterization ineffective.An altemative strategy is the use of intact recombinant chimeric molecules in which homologous segments of the target molecules and non-reactive homologues are systematically substituted for one another coupled with site-directed mutagenesis to identify key epitope residues.