ELISA

Enzyme-Linked Immunosorbent Assay

What is an assay?

• An analysis done on a substance to determine the presence of a target substance and sometimes, the amount of that target substance.

• How do scientists use assays?– To determine the level of thyroid hormones in the

blood if the person is suspected to having hyper or hypothyroidism.

– To determine the potency of a vaccine.

We performed an ELISA!

• It’s just one type of assay (of many) called: Enzyme-linked Immunosorbent assay. The type of ELISA is a sandwich ELISA

• The purpose of a sandwich ELISA is to determine if a particular antigen is present in a blood sample and if so, how much!

How can ELISA’s be used?

• Examples: HIV, Lyme Disease, Rotavirus

• How?– If your blood contains antibodies to any of the conditions above,

your body either has the condition or has had it in the past. In a lab, a technician:

– 1. adds the sample to a microtiter plate containing the specific antigen (foreign substance such as a virus that causes your immune system to respond) related to the condition for which you are being tested. If your blood contains antibodies to the antigen, the two will bind together.

– 2. The technician will check this by adding an enzyme to the petri dish and observing how your blood and the antigen react.

– 3 If the contents of the dish change color, you may have the condition. How much change the enzyme causes allows the technician to determine the presence and amount of antibody.

Check it out!

• http://www.youtube.com/watch?v=2-sVA_b-ivQ

• As you watch the video clip, record the steps in the ELISA!