The EIA enzyme immunoassay is used in laboratories to detect specific antibodies in patient serum. The test works by attaching a particular antigen to a microtiter plate. The patient antibody binds to this antigen, and an enzyme-conjugated secondary antibody binds to a region of the microtiter plate. The secondary antibody recognizes the primary antibody by binding to the antigen-binding site. This process is called indirect ELISA.
EIA has a similar structure to an ELISA, but it differs slightly in assay design. Both techniques use an enzyme as a reporter label. The idea of a bioassay was independently developed by two scientific research groups. Peter Perlmann, Eva Engvall, Anton Schuurs, and Bauke van Weemen developed the ELISA technique. These two groups also worked together to create a variety of biomarker tests, and they were the first to use this technique.
The ELISA uses an enzyme as a substrate, a colorless molecule that is converted into a colored end product. Horseradish peroxidase and alkaline phosphatase are the most common enzymes used in an ELISA. ELISAs can also use a fluorogen, a non-fluorescent molecule that is not normally fluorescent. The fluorescent color can be detected by a spectrophotometer or a fluorescence microscope.
In a recent study, a two-tier algorithm was evaluated in serum samples obtained from 91 patients. The algorithm performed significantly better than standard two-tiered ELISA. During the acute phase, the sensitivity was 37%; during convalescence, the percentage was 89%. The same was true for the late infection period. The algorithm was also equally sensitive when it came to detecting patients with LD and a positive IgG antibody result.
The EIA is generally safe, with very few reports of adverse effects. However, results must be interpreted in relation to the patient's overall health and symptoms. Despite these concerns, the EIA has become a widely-used test in a wide variety of indications. And it can provide information that isn't available through any other test. So, when is an EIA indicated?
The EIA/ELISA developed a variety of new test formats. It began with the immunoenzymometric test (Ref. ( ), and then moved into sandwich test procedures. In reproductive endocrinology, the new EIA systems included human chorionic gonadotropin, total estrogens, and human placental lactogen in plasma. In the late 1970s, the new EIA systems became commercially viable and were adapted to existing RIA systems.
The EIA detecting VlsE has the potential to replace conventional 2-tier testing. Its detection of VlsE lipoprotein and a 26-mer peptide from the sixth invariable region of a protein are both highly sensitive and specific. Single-test approaches have been unable to provide the same level of precision as a two-tiered approach. The EIA may ultimately become the only PCR-based test that can accurately detect certain antibodies and peptides in human serum.
A validated ELISA/AGID has been used to determine steroid hormone levels in blood plasma of equine serum samples. The recombinant p26 protein is produced by a synthetic gene. In addition, the test requires no handling of pathogenic EIAV. This method could prove to be cheaper and more convenient than a commercial ELISA/AGID test, and would also allow for serodiagnosis in India.
Monoclonal EIA has also been validated for the detection of H pylori antibodies in stool. These tests are fast and easy to perform and offer excellent discrimination between positive and negative results. Further studies may also confirm this method's accuracy. They may also be used to study H pylori infection and its incidence and clearance in young children. Therefore, the EIA test may have a place in the pediatric clinic.
Moreover, enzyme immunoassays are used to detect serum anti-IgA antibodies from the IgG class. The enzyme immunoassays used for the test utilize purified polyclonal human serum IgA as the coating antigen, and commercial alkaline phosphatase-conjugated anti-human IgG as the detecting antibody. Individual sample blanks and bovine serum albumin reduce the incidence of nonspecific reactions. Inhibition tests determine the specificity of IgA antibodies, and pooled normal human serum inhibits the presence of specific antibodies by over 80%.
After detection, scientists always clean the Elisa plate with ELISA washer. Elisa washer is a medical device specially designed to clean the microplate and generally used in conjunction with the microplate reader. It has been widely used in the cleaning of ELISA plates.