Question

ELISA test is used to
(a) Separate viral RNA
(b) Purify proteins
(c) Isolate DNA sequences
(d) Identify specific proteins

Answer 1

Hint: ELISA is a laboratory test which is widely used to detect antibodies in the blood. The ELISA has been used in medicine and plant pathology as a diagnostic method, as well as quality-control tests in various industries.

Complete answer:
ELISA stands for Enzyme Linked Immunosorbent Assay. ELISA is a faster approach to detect a specific protein in a cell , tissue, organ, or body fluid than Western blot analysis. This process, which does not involve sample fractionation by gel electrophoresis, is based on the protein properties to bind easily to a plastic surface.
In a given sample it is used to detect the presence of protein antigen and an antibody. The sample that contains a protein is placed on a wall. An antibody that is specific to protein was added and further agglutinates with it. The antibody is bound to a related enzyme to which the substratum of the enzyme is attached. The enzyme works on the substrate and displays a noticeable change in colour that is an indication of the presence of antigen in the sample.
So, the correct answer is, ‘identify specific proteins’.

Additional Information: ELISA is based on the Antigen (Ag) -Antibody (Ab) reaction theory. The Antibody is used as the substrate in this test. The enzyme used for this diagnostic test is horseradish peroxidase. Owing to its reduction, this enzyme converts colourless or non-fluorescent molecules into coloured and/or fluorescent molecules in the presence of unique substrates that serve as hydrogen donors.
Examples of the uses of an ELISA test include diagnosing infections such as HIV (human immunodeficiency virus) and some allergic disorders such as food allergies, and laboratory testing to classify compounds (cell lysate antigens in a wide variety of organisms).

Note: ELISA was the first screening test which was widely used for HIV. It does have a high sensitivity. This test can be used to assess if one has antibodies that are linked to certain conditions of infection. ELISA can be used in a virus test to determine the serum antibody concentrations.