Multiple Antigen Peptide (MAP)

The multiple antigen peptide (MAP) is a recently introduced concept to avoid chemically undefined entity of an antigen-carrier system. The MAP system utilizes a peptidyl core of three or seven radially branched lysine residues, on to which the antigen sequences of interest can be built using standard solid-phase chemistry. The heptalysine core yields the MAP bearing four or eight copies of the peptide epitope (high molar ratio), depending on the inner core that generally accounts for less than 10% of total molecular weight. The MAP system does not require a carrier protein for conjugation. The high molar ratio and dense packing of multiple copies of the antigenic epitope in a MAP has been shown to produce strong immunogenic response. In theory, MAP has an advantage when compared to its monomeric counterpart attached to a carrier protein in that the lysine core of a MAP is small compared with the peptide antigen. Therefore, the concentration of antigen is at a maximum. The result is a highly immunogenic MAP, which exhibits significantly higher titers when compared to its monomeric counterpart attached to a carrier protein. Since the peptide is linked through the C-terminus, the MAP technique favors to the production of antibodies N-terminal or internal peptides and is not recommended for peptides from the extreme C-terminus of the native protein. The carrier attachment may also cause some steric hindrance toward antibody production to the C-terminus. Cysteines can be problematic in that disulfide bonds can form non-specifically and C-terminal prolines give poor yields with this chemistry.