What is an ELISA test?
Enzyme-Linked Immunosorbent Assays (ELISAs) are the most widely used type of assay. They have evolved from viral lysate tests to tests containing recombinant protein and synthetic peptide antigens:
- They have high sensitivity and specificity.
- ELISAs are designed specifically for screening large numbers of specimens at a time, making them suitable for use in surveillance and centralized blood transfusion services.
- As ELISAs require sophisticated equipment and skilled technicians to perform the tests, their use is limited to certain circumstances.
Although there are a number of documents published on method validation (1, 2) which target analytical methods in general, and there are numerous publications on validation of ELISA methods for pesticides, these documents do not address specifi c areas of concern for food allergen analysis, such as reference materials, spiking methods, or choice of matrixes. In the absence of a universally recognized reference standard for food allergen ELISAs, many organizations and end-users use different validation protocols and different analytical standards. Such inconsistency and duplication inevitably has a negative economic impact on the food allergen community. This document is designed to accompany the AOAC Guidelines for Collaborative Study Procedures to Validate Characteristics of a Method of Analysis (1), and to provide guidance specifi c to the validation of quantitative ELISAbased methods for food allergens. This protocol was designed to meet or exceed the minimum requirements set forth in the AOAC guidelines; it was developed with input from a wide range of experts in the area of food allergens, working under the auspices of the AOAC Presidential Task Force on Food Allergens and with the active contribution of the Allergen Working Group, part of the MoniQA network of excellence. This document will focus on developing guidance on a method validation study protocol to validate the performance characteristics of quantitative food allergen ELISA methods. The practical protocol is intended to help method developers in designing a study to generate appropriate validation data that would be suitable for submission to AOAC INTERNATIONAL or regulatory bodies for recognition.
The ability of an ELISA method to detect food allergen proteins in a test sample is affected by the effi ciency with which these proteins are extracted from the sample, as well as the effi ciency with which the antibody or antibodies used in the ELISA detect these proteins in the sample extract. The overall performance of an ELISA-based method for the detection of food allergens is a function of these two parameters.
The food allergen analytical community is challenged to develop detection methods for multiple allergens in various food products to protect allergic consumers and promote consumer confi dence. This protocol refl ects the consensus reached through input from various food allergen analytical experts and contains recommendations based on the current knowledge of ELISA methods. Specifi c recommendations have only been included for two priority allergens, egg and milk. The general considerations of the protocol will be applied to other priority allergens in the future. Meeting the challenges of developing reliable food allergen detection methods requires conscientious and continuous support from the allergen community. Future work is planned for the implementation of this guidance document for egg and milk ELISA methods and for the development of similar guidance pertaining to other priority food allergens.
