Topic 5: ELISA

• Immune system - a system in our body that protects us from pathogens and is an inflammatory response
• antigen - protein molecule that stimulate immune system to produce antibodies
• Epitopes - it is an antigenic determinant
• Haptens - smallest chemical moiety of an epitope
• Antibodies - it is only produced with the presence of antigen; to fight infection or cancer
• paratopes - antigen-binding site in antibodies
• cross-reacting - ability of antigen to bind to antibody
• Light chains - variable region of antibody where antigen-binding sites are located
• Types of ELISA

  • Direct
  • Indirect
  • Sandwich
  • Competitive
• direct ELISA - most common and simplest
• Format of Direct ELISA

  • Antigen bind to
  • Antibody conjugate
  • Substrate
• Indirect ELISA - almost the same as direct ELISA but there is a presence of primary antibody
• Format of Indirect ELISA

  • Antigen
  • Bind to Primary antibody
  • Add Secondary antibody conjugate
  • substrate
• Sandwich ELISA - also known as capture assay; antigen is being sandwich into the antibodies
• Format of Sandwich ELISA

  • Captured Antibody
  • Antigen
  • Primary Antibody
  • Secondary Conjugate
  • Substrate
• Polystyrene chemical - used in microplate strip to make the antigen stick
• Tetramethylbenzidine substrate - it attaches to the enzyme to make a change in color and to make the antigen and antibody detectable