Question

A certain patient is suspected to be suffering from acquired immuno deficiency syndrome. Which diagnostic technique will you recommend for its detection?

• A. MRI
• B. Ultrasound
• C. WIDAL
• D. ELISA

Answer 1

The correct option is D ELISA

ELISA stands for Enzyme linked immunosorbent assay. It is a diagnostic technique used for the detection of acquired immuno deficiency syndrome (AIDS). ELISA is an extremely sensitive test that is used to detect antibodies (Ab) or specific antigens (Ag). It is carried out in a 96 well microtiter plate. The direct ELISA is a test for the presence of antigen. In this procedure, a known antibody is adsorbed to the inside of the well in a microtiter plate. After rinsing to remove excess antibody, the sample suspected of containing the antigen is added. Next, an enzyme linked Ab that can react with Ag is added. If Ag is put in the well, the enzyme linked Ab binds to it and is retained. The colourless substrate for the enzyme is added. Development of colour indicates the presence of the Ag.

In indirect ELISA, Ag is added to the microtiter plate well and the Ag attaches to the walls of the microtiter plate. After rinsing to remove excess Ag as the serum suspected of containing the Ab is added. Enzyme linked antibody capable of reacting with the constant region of other Ab is then added, followed by addition of the colourless substrate. Development of colour indicates the presence of Ab being identified.