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| Diagnostic Kits - Enzyme - Linked Immunosorbent Assay (ELISA) |
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| ELISA technique is widely used for the detection of viruses, fungi, bacteria etc. It is a very sensitive and specific test and needs a very small amount of reagents. It is used to detect the infectious diseases like tuberculosis, AIDS etc. |
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| The diagnostic kit detects the presence of an antigen or antibody in a sample by antigen - anti body interaction. |
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| The procedure |
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| The antibody, which is specific to the antigen to be detected must be present in the kit. The sample, which is suspected to contain the antigen is immobilised on the ELISA plate. The specific anti body is added and allowed to react with the antigen. Washing will remove all free antibodies. The antibodies, which are bound to the antigen will remain. Now an anti-immunoglobulin is added and allowed to react with the antibody bound to the antigen. |
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| On washing the unreacted anti-anti body is removed. The anti-anti body is linked to an enzyme For e.g., peroxidase. Activity of the enzyme yields a coloured product. The colour indicates the presence of the antigen. The deeper the colour, more is the amount of the antigen. ELISA can detect even a very small amount of antigen. |
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| It is a very useful kit to diagnose HIV infection. It is applicable to many other antigens also. |
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