Epitope Mapping

The aim of epitope mapping is to find out which part of its antigen a given antibody binds to, and mapping methods are most widely applied to protein antigens. It is possible to think of epitope mapping as a “simple” biochemical problem of finding out how one well-defined protein (a monoclonal antibody [MAb]) binds to another (the antigen). The term “epitope mapping” is also used to describe the attempt to determine all the major sites on a protein surface that can elicit an antibody response, at the end of which one might claim to have produced an “epitope map” of the protein antigen. This information might be very useful, for example, to someone wishing to produce antiviral vaccines. However, it is questionable how far one can go down this road, since the final map will depend on the individual immune response (although immunodominant regions undoubtedly exist) and on how MAbs are selected, and may depend also on the mapping method used. Epitope mapping is usually done with MAbs, though it can be done with polyclonal antisera in a rather less rigorous way, bearing in mind that antisera behave as a mixture of MAbs of variable complexity. Some authors have extended the epitope concept to the interaction between peptide hormones and their receptors ( 1 ); however one feels about this, it does make the point that in mapping epitopes, we are studying a biological process of fundamental importance, that of protein—protein interaction.