What is ELISA kit procedure?
ELISA is short for enzyme linked immunosorbent assay and it is frequently used by various laboratories to detect many different types of antibodies. An antibody is defined as a protein molecule that is produced by the human immune system to combat foreign and in many cases harmful substances which are known as antigens.
ELISA is a procedure that allows scientist to detect the concentration of a specific analyte (this can either be an antigen or an antibody molecule) that is present within a sample solution. This ELISA kit method can be carried either in a 96 or a 384 well polystyrene plate format. The wells are coated with a specific antibody or antigen that will bind to a known protein or antibody that is present within the sample solution. The main steps of ELISA are:
- Binding and immobilisation of antibodies or proteins
- Blocking step to coat all the unbound wells
- Repeated washing steps to remove any non-specific binding
- Addition of substrate to produce a calorimetric signal
- Reading the plate
The following steps of ELISA will result in the production of a coloured end-product that will be directly correlating to the concentration/amount of analyte that is present within the original sample.
This method is growing in popularity because of the many advantages it offers over other procedures. For example: the reagents used tend to have a long shelf life, reagents are easy to handle and free from any radiation risks that may be linked with waste substances, it is a totally flexible system that allows multiple samples to be detected over a short time frame, each kit is fully optimised and requires very little technical training to perform the assay and it is a relatively low step-up cost to carry out the tests.
ELISA kit applications
The ELISA procedure is commonly used in a wide range of applications and these can include the following:
- Diagnosis protocols: During the diagnosis of various applications the ELISA method has proven to be instrumental tool to allow the detection of many types of diseases that can be present in large number of species (including humans and many different animals). In humans it is used as a biomarker for detecting cancer, infectious diseases, autoimmunity, endocrinology diagnostics, immunology and cytokines, cell adhesion molecules (CAMs), cardiac markers, diabetes, nephrology, thyroid function, fertility, growth factors, bone and mineral metabolism, apoptosis, matrix metalloproteinases (MMPs), biogenic amines, food safety and analytics.
- Detection of cancer: This process enables the detection of many cancers at the early stage of the diagnostic process. This will offer a better chance of patient survival and obtaining appropriate treatment at an early stage of the cancer. There are many cancer biomarkers that are now available for ELISA assay procedures and this list continues to grow at a rapid rate.
- The development of vaccines: The ELISA method provides a useful tool during the development of new vaccines. In many cases the serum sample from an immunised human or animal model can be used in the detection of specific antibodies present within the organism against certain types of antigens. This can be done under controlled experiments where specific antigens of interests are intentionally injected into the host organism. However, it is often a difficult task to select the appropriate assay for developing vaccines. To choose a suitable assay that matches and correlates with the disease or protection against infection is difficult since the human immune response is complex multi-dimensional and polyclonal by nature.
- Food testing: ELISA assays can be used to detect the allergen protein molecules through the process of binding antibodies to the allergen of interest and then detecting the colorimetric change. Manufacturers are now required to label their products in relation to eight specific allergens and these are: peanuts, tree nuts, soybeans, eggs, wheat, milk, fish and shellfish. These eight allergens have been reported to be responsible for more than 90% of all the identified food allergen cases reported. The product testing procedure within the food industry for many decades has been focused on the detection of contaminants which may result in illness or lead to outbreaks. In majority of cases fungal and bacterial pathogens were the main agents, this was followed by various chemical contaminants. However, with the modern development in technology with the potential of automation and high-throughput processing, additional contaminants such as food allergens have been a major issue for food safety.
- Pregnancy testing: There are many biological markers that are expressed due to pregnancy. These biomarkers include: follicle stimulating hormone (FSH), thyrotropin stimulating hormone (TSH), luteinizing hormone (LH), estriol (E3) and human chorionic gonadotropin (hCG). The ELISA assay method can be used to detect all these proteins present in saliva, urine and maternal blood during the early stages of pregnancy. For example: detecting estriol (E3) using saliva samples can be made at the 6th week stage of pregnancy or hCG can be detected in the first month after the fertilization process.
Due to the increasing number of new diseases that are being encountered by the global population and the need to make early diagnosis, this will lead to a greater reliance on the use of ELISA kit procedures. Immunoassays offer a means of quality control and a suitable method for carrying out the diagnostic process quickly, this will further increase the demand for ELISA kits in the future. Some of the main markets will include the pharmaceutical industry in the development of novel vaccines and drug formulations, allergy testing in the food industry because of the increasing health-conscious population and combating new viral infections to fight off any future pandemics.
- ELISA Principle
- ELISA Protocol
- Analysing ELISA Data
- General ELISA FAQ
- ELISA Trouble Shooting FAQ
- Comparison Between ELISA And EIA
- ELISA Sample Preparation
- Different ELISA Detection Strategies
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