What is the main purpose of enzyme-linked immunosorbent assay (ELISA) in diagnosing AIDS?

To detect the presence of HIV antibodies in the blood

The correct answer is a) To detect the presence of HIV antibodies in the blood.

Enzyme-linked immunosorbent assay (ELISA) is a commonly used diagnostic test for AIDS (Acquired Immunodeficiency Syndrome) or HIV (Human Immunodeficiency Virus) infection. Its main purpose is to detect the presence of HIV antibodies in the blood sample of an individual.

When a person is infected with HIV, their immune system produces specific antibodies against the virus. These antibodies can be detected using the ELISA test. The test involves coating a solid surface, such as a plate, with HIV antigens. The patient's blood sample is then added to the plate, and if HIV antibodies are present in the blood, they will bind to the antigens on the plate.

Afterward, an enzyme-linked secondary antibody is added, which will bind to the HIV antibodies if they are present. The enzyme attached to the secondary antibody reacts with a substrate, producing a detectable signal, typically a color change. The intensity of the signal indicates the presence or absence of HIV antibodies in the blood sample.

ELISA is a sensitive and specific test for detecting HIV antibodies and is commonly used in screening blood donations, diagnosing HIV infection, and monitoring the progression of the disease. If the ELISA test yields a positive result, further confirmatory tests, such as Western blot or PCR (Polymerase Chain Reaction), are usually performed to confirm the HIV infection.