A peptide is usually too small to elicit a satisfactory immune response in animals. In order to improve immunogenicity, one needs to attach the target peptide to a larger macromolecular structure. While protein carrier conjugation remains the preferred approach, the MAP (multiple antigen peptide) is used in some instances.
Peptide epitopes are covalently conjugated to a larger carrier protein and the latter conjugate is used as immunogen to generate antisera.
Standard carrier is (Keyhole Limpet Hemocyanin-KLH), however other proteins are available for conjugation (Bovine Serum Albumin- BSA, Ovalbumin-OVA, etc.).
Multiple antigen peptides (MAP) immunogens contains 8 copies (or 16 copies) of the peptide, synthesized directly on an 8-armed (or 16-armed) branched lysine core. The resulting multimeric is a large macromolecule (10-15 kDa) which has a high molar ratio of peptide antigen to core molecule and does not require further conjugation to a carrier protein. We typically prepare 10-20 mg of these MAP.