Enzyme-linked immunosorbent assay is a laboratory study, which is based on the identification of antigen-antibody complexes using a special enzymatic label, which is detected due to a change in the color of the substrate. The main goal of this analysis is to determine the presence of various products of enzymatic reactions in test samples.
To detect antigens and antibodies, a heterogeneous enzyme-linked immunosorbent assay is used, since in its process it is easy to separate the components of the reaction and retain some of them in the solid phase.
It is worth noting the following advantages of this laboratory study :
• high sensitivity, which allows even a small number of molecules of the corresponding substances to be detected;
• to conduct this analysis, you can use the minimum number of test material;
• the ability to save for a long time all the components that are necessary for the analysis;
• ease of implementation;
• the presence of instrumental and visual results;
• enzyme immunoassay is automated at each stage of the reaction;
• relatively low cost of kits used for diagnostics.
These advantages make it possible to widely use ELISA in various fields of medicine, including for the diagnosis of viruses.
The most common technique for immobilizing antibodies and antigens is the adsorption reaction, when individual molecules attach to the solid phase (due to ionic or hydrophobic interactions or due to the formation of a hydrogen bond).
I must say that enzyme immunoassay is used in two cases:
• to identify antigens of pathogens of various infections;
• to determine the presence of antibodies to the antigen of pathological microorganisms (it is worth noting that using ELISA can detect almost any sexual infection).
To conduct this serodiagnosis, a special polystyrene tablet is used. It has 96 holes, on the side surfaces of which antigen is adsorbed. When the test serum is introduced into the plate cells, the corresponding antibodies are attached to the antigen. Subsequent addition of a labeled antibody to human immunoglobulins to the wells undergoes a specific reaction. At the next treatment of serum with a chromogen (dye), the color of the substrate changes (in the presence of the corresponding antigen-antibody complexes). It is worth noting that the color intensity is directly proportional to the number of antibodies.
ELISA analysis ends with a measurement of the
optical density of the liquid in the cells of the tablet. At the same time, they use special devices and template samples that help to calculate the concentration of antibodies. It should be remembered that each test system for carrying out this analysis has its own values of normative indicators (this, as a rule, is prescribed in the results that are issued on hand).
With the help of ELISA, syphilis, viral hepatitis and HIV infection are diagnosed, as well as cytomegalovirus, chlamydia, herpes (various types) are found in the human body. This analysis also helps to determine the level of hormones, to identify cancer markers.
Where to take tests in Moscow? Today, there are many specialized laboratories that offer a wide selection of serological studies. To get directions, you should consult your local clinic doctor (or the private specialist you are looking at). You should also go to the doctor with the test results. And listen to his comment regarding the need for any treatment.