Enzyme Linked Immunosorbent Assay (Direct)
What is ELISA TEST ?
ELISA Test is commonly used to test antigen antibody protein glycoprotein present in body.
This test is more commonly used than Radioactive Immunoassay (RIA) because of it s simplicity.
How is Direct ELISA performed for antibody detection?
ELISA is performed in special plate for detection of antibody by Direct ELISA steps are as Follows
1) The plate is coated with specific antigen against which the antibody is to be detected
2) Then the serum is added in the plate (serum contains various antibody)
3) Now if the Antibody is present in the serum it will bind to antigen coated in the plate tightly
4) The plate is now washed so that unwanted antibody and other products are washed away and only Antigen-antibody complex remains
5) The antibodies are coated with special enzyme which gives colorful products on reactions with substrate
6) The substrate are added to the plate and if the antibodies are present then it will give colorful product and thus by this way we can confirm the presence of antibodies.
7) For measuring the quantity of antibodies spectrometer detects the Intensity of color and measures quantity of antibodies.
Pros:
1) Direct ELISA is quicker than any other tests performed
2) It is very simple test which does not require polyclonal or monoclonal antibodies as in Indirect test
Cons:
1) Enzyme linked antibodies are assumed to be less reactive with antigen so if quantity of antigen is less margin of error in this test is Increased.
2) As one antibody coated with one enzyme the color products are less in concentration thus Sensitivity of this test is presumably less
The Cons of DIRECT ELISA are rectified by INDIRECT ELISA TEST.

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