antibodyepitope

An antibody epitope is the part of an antigen that is specifically recognized and bound by an antibody. The antibody has a binding site, called the paratope, that interacts with the epitope to form an antigen–antibody complex. An antigen can display multiple epitopes, each potentially recognized by a different antibody.

Epitope types are broadly categorized as linear (continuous) or conformational (discontinuous). Linear epitopes consist of a short, continuous stretch of amino acids, while conformational epitopes are formed by amino acids that are brought into proximity in the folded three-dimensional structure of the protein, and may be distant in the primary sequence. Accessibility on the antigen surface is important for epitope recognition; post-translational modifications such as glycosylation can mask or alter epitopes and influence antibody binding.

Understanding epitopes is central to immunology. Antibody specificity is defined by the epitope, and related epitopes can lead to cross-reactivity if they share similar features. Epitope identification and mapping—via peptide libraries, phage display, mutagenesis, or structural methods such as X-ray crystallography and cryo-EM—helps reveal which residues contribute to binding and how the interaction occurs.

Applications of epitope knowledge include vaccine design, diagnostic assays, and the development of therapeutic monoclonal antibodies. Epitope data guide strategies to enhance immunogenicity, improve specificity, and predict potential cross-reactivity among related antigens.