VMC 221: Veterinary Immunology and Serology (1+1)

Antigenic determinants or Epitopes

ANTIGENIC DETERMINATS OR EPITOPES

• An antigen will evoke immune response in a specific host.
• The antigenic specificity is determined by Epitopes, the smallest unit of antigenicity.
• Epitopes are some specific areas or chemical groupings with steric (spatial) configuration present on the surface of antigen molecule.
• Epitopes are capable of sensitizing an immunocyte and reacting with its complementary site on the specific antibody or TCR.
• The combining area on the hypervariable region of antibody molecule that corresponds to epitopes is called paratope or idiotope. On T cells the recognition site is termed as Agretope.
• Epitopes and paratope determined the specificity of immunological reaction.
• Epitopes are also called antigenic determinants.
• Most epitopes have 6 to10 amino acids (T cell epitopes) or 10-15 amino acids (B-cell epitopes )