ELISA ELISA Understanding the Acronym EL EnzymeLinked An

ELISA

ELISA (Understanding the Acronym) • EL = Enzyme-Linked – An enzyme’s activity is used as a “reporter” to test for the presence/amount of a protein of interest. – The enzymatic reaction will produce a colored result.

ELISA (Understanding the Acronym) • EL = Enzyme-Linked • IS = Immunosorbent – An antibody or antigen (“immuno”) is adsorbed (“sorbent”) onto the polystyrene wells in which we conduct the test.

ELISA (Understanding the Acronym) • EL = Enzyme-Linked • IS = Immunosorbent • A = Assay – An assay is a test that allows you to observe the binding or presence of a biological molecule

Uses for ELISA • ELISA is used to test for the presence of larger molecules such as proteins and hormones b/c their big and easier to capture • ELISA can be used to: – Identify disease causing agents – Detect viruses – Identify allergens in food systems – Confirm pregnancy – Identify illegal drug use • There are many different types of ELISA, the one we will focus on is an INDIRECT ELISA

• Antibodies = immune system-related proteins called immunoglobulins, each antibody consists of four polypeptides (2 heavy chains & 2 light chains joined to form a "Y" shaped molecule) • The amino acid sequence in the ends of the "Y" varies greatly among different antibodies giving the antibody its specificity for binding antigen. – Antigen = a foreign substance that induces an immune response • The constant region determines the mechanism used to destroy antigen • Antibodies are divided into five major classes, Ig. M, Ig. G, Iga, Ig. D, and Ig. E Antibodies & Antigens

Indirect ELISA • The wells in your plate have been coated with a protein with a primary antibody attached to the protein • A secondary antibody linked with an enzyme is attached to the primary antibody • If you add a substrate ( a substance on which an enzyme acts such as blood, saliva, etc. ) that has a disease causing antigen, the antigen and enzyme react to produce a color change indicating a positive result