EnzymeLinked Immunosorbent Assay ELISA MultiLingual Captions




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The enzyme-linked immunosorbent assay or ELISA is a commonly used format for serologic testing. The purpose of this animation is to explain how this test works. ELISA serologies are usually done in multi-well microtiter plates so that dilutions of serum can be easily prepared and tested. To better understand how this assay is done, lets take a closer look at what happens in one of the wells of this assay plate. To perform the assay, the wells of the plate are coated with the antigen of interest. For commercial tests, this would be done by the manufacturer of the assay. To begin testing, the wells are filled with dilutions of the patient's serum. If antibodies against the antigen are present they will bind to the antigen fixed to the bottom of the wells. But only antigen-specific antibodies will bind to the wells. The wells are then washed out to remove all unbound antibodies. Next a solution of an animal antibody against human antibodies is added. This second antibody is covalently conjugated to an enzyme. The wells are washed again, this time to remove any unbound enzyme-conjugated antibody. Finally a solution of a colorgenic enzyme substrate is added. The interaction of the substrate with the enzyme on the second antibody generates visible color. The development of color in the wells with a specific antibody can be seen with the naked eye or quantified with an electronic plate reader. The reaction is less intense as the serum is diluted and the amount of antibody captured in the wells decreases. The titer is the highest dilution with definite color development. Subtitles by the Amara.org community