Question

Home pregnancy tests utilize elisa technology. when a woman is pregnant, her body produces a hormone called human chorionic gonadotropin (hcg). explain how antibodies can be used to detect this hormone and are linked to a color change a woman may see on a positive test.

Answer 1

The pregnancy test kits works on the principle of sandwich ELISA.

The hCG present in the urine sample is allowed to react with the monoclonal antibodies present in the testing kit. This monoclonal antibody is specific for the hCG. The reaction of hCG and the antibody forms a complex.

In the detection plate, a secondary antibody is also present, which bind to the Fc region of the monoclonal antibody, hence, creating a sandwich. This secondary antibody can give the color, when antibody is bind to the hCG, or the antigen antibody complex is formed. The intensity of the color is dependent on the amount of hCG present in the sample.