Enzyme-linked immunosorbent assay indirect

Positive enzyme-linked immunosorbent assays are repeated in duplicate and if one or both tests are reactive, a confirmatory test is performed for final diagnosis. Western blot assay is the most commonly used confirmatory test, although an indirect immunofluorescence assay is available. 

Enzyme-linked immunosorbent assays. An indirect application of enzymes in analysis is as a marker or label in enzyme-linked immunosorbent assays (ELISA). In ELISA, the enzyme does not react with the analyte instead, an antibody is raised against the analyte (antigen or hapten) and labelled with easily assayed enzyme, usually a phosphatase or a peroxidase. The enzyme activity is proportional to the amount of antibody in the system, which in turn is proportional, directly or indirectly depending on the arrangement used, to the amount of antigen present (Morris and Clifford, 1984). 

Indirect competitive enzyme-linked immunosorbent assay... 

Pinacho, D.G., F. Sanchez-Baeza, and M.P. Marco. 2009. Development of a class selective indirect competitive enzyme-linked immunosorbent assay (ELISA) for detection of fluoroquinolone antibiotics. J. Agric. Food Chem. submitted. 

A partially purified Bacillus thurlnglensis var. israelensls (Bti) 6-endotoxin was used to Immunize rabbits. The antisera obtained have an improved specificity towards the mosquito larvacidal activity of the toxin, as opposed to antiserum raised when the whole crystal was used as immunogen. Using a two step/indirect ELISA (enzyme linked immunosorbent assay) procedure developed in our laboratory, fourteen experimental formulations were tested, and the results were compared with bioassays. An average of 69.1 international units 20% c.v. was found to associate with each ug of toxin detected by the ELISA. Our data indicate that when toxin specific antisera are available, Immunoassays can be used to predict the biological activity of Bti samples with reasonable accuracy. 

The causative agent in Lyme disease is a spirochetal bacterium (Borrelia burgdorferi) that is transmitted directly through the bite of a deer tick. Optic neittopathy can occur due to Lyme disease and manifests as papillitis, retrobulbar neuropathy, or ischemic optic neiu-opathy. Serologic testing may help to identify Lyme infection by use of indirect immunofluorescent assay and enzyme-linked immunosorbent assay.The treatment of Lyme disease includes oral or intravenous peniciUin, doxycycUne, erythromycin, or ceftriaxone. 

An indirect enzyme-linked immunosorbent assay (ELISA) was developed for maduramicin in poultry feed. The assay utilized polyclonal anti-maduramicin antibody raised in rabbits, maduramicin monoamide with 1,6-hexane diamine-conjugated ovalbumin as the coating antigen, horseradish peroxidase conjugated goat anti-rabbit IgG and 2,2 azinobis(3-ethylbenzthiazoline) sulfonic acid (ABTS) for quantitation. Standard curves ranging from 0 to 80 ng/mL maduramicin were constructed. The assay did not cross-react with monensin, lasalocid, salinomycin, lincomycin, narasin, chlortetracycline or roxarsone. Broiler feed fortified at 4 to 7 ppm maduramicin were shown to be quantifiable by ELISA at an average recovery of 98.1%. This ELISA method for maduramicin in poultry feed is comparable to the established HPLC-F method. 

Leiby, D.A. et al. Serologic Testing for Trypanosoma cruzi Comparison of radioimmunoprecipitation assay with commercially available indirect immunofluorescence assay. Indirect hemagglutination assay, and enzyme-Linked immunosorbent assay kits. J Clin Microbiol 2000 38 639-42. 

Cell-enzyme-linked immunosorbent assay (cell-ELISA) is an useful technique for the quantitative analysis of cell surface antigen expression that was developed on the basis of enzyme immunohistochemistry (EIH) and ELISA. Since its development, which was made possible by the establishment of monoclonal antibody technology, a wide range of cell types and surface molecules were analyzed by cell-ELISA. Here we show four variants of this method and provide a brief comparison of cell-ELISA with flow cytometry (FACS) and radioimmunobinding assay (BIA), which are other methods for the quantitative detection of cell-surface molecules. We describe step-by-step procedures for both direct and indirect cell-ELISA using either adherent or nonadherent live cells. 

Uhaa IJ, Fishbein DB, Olson JG, et al. Evaluation of specificity of indirect enzyme-linked immunosorbent assay for diagnosis of human Q fever. J Clin Microbiol. 1994 32 1560-1565. 

Fan TSL, Zhang GS, Chu FS. An indirect enzyme-linked immunosorbent assay for T-2 toxin in biological fluids. Journal of Food Protection. 1984 47 (12) 964—967. 

Competitive enzyme-linked immunosorbent assays (ELISA) Two types of ELISA have been used for the analysis of mycotoxins and both types are heterogenous competitive assays. One type, i.e. direct ELISA, involves the use of a mycotoxin-enzyme conjugate and the other system, i.e. indirect ELISA, involves the use of a protein-mycotoxin conjugate and a secondary antibody to which an enzyme has been conjugated. Although horseradish peroxidase (HRP) is most commonly used as the enzyme for conjugation, other enzymes such as alkaline phosphatase and beta-galactosidase, also have been used (5, 9, 13). 

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