Detection of Microbial toxin by enzyme-linked immunosorbent assay (ELISA)

The common kits available are, enzyme-linked immunosorbent assay (ELISA). Basically each different species of microorganism or toxin have at least one unique antigen. These antigens could be purified and used to produce specific antibodies.  The antigens and antibodies are useful and precise diagnostic tools. The enzyme-linked immunosorbent assay (ELISA) is a technique commonly used to detect the presence of that particular antigens or antibodies.  The direct ELISA utilizes antibodies to identify the existence of a specific antigen in a sample.
Firstly, a specific antibody will be attached onto the walls of a microtiter plate. Next, the sample will be added into the well to examine the presence of complementary antigen. If the particular antigen is present in the sample, it will attach to the antibodies on the surface of the well. The microtitler plate will be rinsed, and is able to remove any unbound antigen. Next, will be the addition of the monoclonal, modified antibody that is linked to an enzyme (enzyme conjugated antibody). The well will be rinsed again to remove any unbound antibodies. If the particular antigen is not there, the enzyme conjugated antibody will be washed away as it is unable to bind to the antigen. Lastly, the enzyme’s substrate will be added and its purpose is to create a colour change if the enzyme conjugated antibody had reacted with the substrate. No colour change represents a negative result.

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