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Elisa Kits - Accurate, Sensitive and Specific

Author: Block Scientific
by Block Scientific
Posted: Feb 19, 2016

Enzyme-linked Immunosorbent Assay (ELISA) is a biochemical procedure that is used for detecting and quantifying the presence of substances such as such as peptides, proteins, antibodies, antigens and hormones in a liquid or wet sample. Leading manufacturers of laboratory products offer a wide variety of ELISA kits to help detect cancer, autoimmune diseases, infectious diseases, chronic medical conditions, allergies and more. They come in a wide range of formats such as colorimetric, fluorescence, and chemiluminescence.

What is the ELISA Mechanism?

Primarily used in diagnostics, particularly in the areas of autoimmune disorders, fertility, infectious ailments, plant pathology, diabetes assays, food allergens, toxicology, and virus tests, the ELISA kit utilizes components of the immune system and chemicals to detect immune responses in the body, such as the response to an infectious microbe.

ELISAs can be performed with a number of modifications to the basic procedure. Performing an ELISA test requires at least one antibody with specificity for a particular antigen. The sample with an unknown amount of antigen is immobilized on a solid support usually a polystyrene microtiter plate). Once the antigen is immobilized, the detection antibody is added, forming a complex with the antigen. The detection antibody can be covalently linked to an enzyme, or can itself be detected by a secondary antibody that is linked to an enzyme through bioconjugation. The most crucial element of the detection strategy is a highly specific antibody-antigen interaction.

The different ELISA assay formats include -

  • Direct assay - Direct assay method uses a labeled primary antibody that reacts directly with the antigen. It can be performed with antigen that is directly immobilized on the assay plate or with the capture assay format.
  • Indirect assay - This is the most popular format for ELISA that uses a labeled secondary antibody for detection. The secondary antibody has specificity for the primary antibody.
  • Competitive assay - ELISA can also be performed as a competitive assay when the antigen is small and has only one epitope, or antibody binding site.
  • Sandwich/capture assay - This is one of the most powerful ELISA assay format where in the analyte to be measured is bound between two primary antibodies - the capture antibody and the detection antibody.

Benefits of Using ELISA Kits

Leading manufacturers offer wide range of ELISA kits for different applications. This innovative laboratory technique offers many advantages for physicians, clinical laboratories and research facilities -

  • Quick and accurate
  • Highly sensitive
  • Simple to perform
  • Needs just a simple blood sample obtained either from the arm or fingertip of the patient
  • Easily automated
  • Convenient and easy-to-use for HIV screening
  • Compares favorably with other methods such as radioimmune assay (RIA) tests (do not need radioactive substances or a costly radiation counting apparatus)

Different Types of ELISA Kits

  • Adenovirus IgA, 96 wells - Manufactured by DRG International Inc., this Kit provides materials for determination of IgA-class antibodies to Adenovirus in serum. This assay in mainly intended for research purposes only.
  • Adenovirus IgM, 96 wells - Intended for in vitro use only, the DRG Adenovirus IgM EIA Kit provides materials for the qualitative and semi quantitative determination of IgM-class antibodies to Adenovirus in serum.
  • Salivary 17-OH-Progesterone, 96 Wells - This is mainly used for the quantitative in vitro diagnostic measurement of active free 17-hydroxyprogesterone in saliva.
  • Androstenedione, 96 Wells - This EIA kit is used for the quantitative in vitro diagnostic measurement of Androstenedione in serum and EDTA plasma.

While ELISA tests are accurate, sensitive and specific, false positives and false negatives can occur. Therefore, physicians recommend repeating the test after a few weeks. ELISA test results are also generally compared with another independent method of detecting pathogen presence. The results from the enzyme linked assay and the reference are compared and a threshold is selected which provides the most accurate results.

About the Author

Block Scientific, a leading laboratory equipment supplier in New York, offers a range of new and used lab equipment from industry leading manufacturers.

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Author: Block Scientific

Block Scientific

Member since: Feb 19, 2015
Published articles: 31

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