ELISA is a medical jargon that is confusing especially to those people who are not medical practitioners. What is the phrase all about? What does it signifies? ELISA is a primary tool of clinical immunology which is used as a preliminary screen for HIV detection. HIV or human immunodeficiency virus causes AIDS (Acquired Immunodeficiency Syndrome) which is a disease that makes it difficult for the body to fight off infectious diseases. HIV can be transmitted through direct contact with the blood or body fluid of someone who is infected with the virus. Thus, HIV ELISA which is also called as HIV enzyme immunoassay (EIA) is the appropriate test to determine if an individual is positive for a selected pathogen. The test is performed in a 8 cm x 12 cm plastic plate which contains an 8 x 12 matrix of 96 wells, each of which are about 1 cm high and 0.7 cm in diameter.
Because ELISA can be performed to weigh up the presence of antigen or even the presence of antibody in a sample, it has also found applications in the food industry in distinguishing potential food allergens such as peanuts, almonds, walnuts, milk, and eggs. Not only that, ELISA can be used in toxicology as a quick presumptive screen for certain classes of drugs.
Because EIA or Enzyme Immunoassay test is used to distinguish and calculate specific antigen-eliciting molecules involved in biological processes, it can be used too on most types of biological samples such as that of plasma, urine, serum and cell extracts. In the assay, a plate is coated with a most important antibody, which recognizes the antigen of the target molecule and bonds with it. The antigen-antibody complex is recognized by a minor antibody that is joined to an enzyme that catalyzes the reaction mixture, deferring a specific color. By measuring the optical density of this color, the occurrence and number of a specific molecule can be determined; the density of color is proportional to the advancement of the reaction or disease being tested.
If an ELISA test is used for drug screening at workplace, a cut-off concentration, 50 ng/mL, is ascertained, and a sample will be prepared which contains the average application of analyte. Unknowns that generate a signal that is stronger than the known sample are “positive”. Those that generate weaker signal are “negative”. Also, ELISA test is done for increasing community consciousness of any disease, promoting recognition of its warning signs to seek treatment and further more to provide information with regards to the accessibility of appropriate professional services locally and farther afield.
