Identifying food proteins with allergenic potential: evolution of approaches to safety assessment and research to provide additional tools.

A safety assessment process exists for genetically engineered crops that includes the evaluation of the expressed protein for allergenic potential. The objectives of this evaluation are twofold: (1) to protect allergic consumers from exposure to known allergenic or cross-reactive proteins, and (2) protect the general population from risks associated with the introduction of genes encoding proteins that are likely to become food allergens. The first systematic approach to address these concerns was formulated by Metcalfe et al. [Metcalfe, D.D., Astwood, J.D., Townsend, R., Sampson, H.A., Taylor, S.L., and Fuchs, R.L. 1996. Assessment of the allergenic potential of foods from genetically engineered crop plants. Crit. Rev. Food Sci. Nutr. 36(5), 165-186.] and subsequently Food and Agriculture Organization of the United Nations/World Health Organization (FAO/WHO) [FAO/WHO, 2001. Evaluation of allergenicity of genetically modified foods. Report of a Joint FAO/WHO Expert Consultation on Allergenicity of Foods Derived from Biotechnology. January 22-25, 2001. Rome, Italy]. More recently, Codex [Codex Alimentarius Commission, 2003. Alinorm 03/34: Joint FAO/WHO Food Standard Programme, Codex Alimentarius Commission, Twenty-Fifth Session, Rome, Italy, 30 June-5 July, 2003. Appendix III, Guideline for the conduct of food safety assessment of foods derived from recombinant-DNA plants, and Appendix IV, Annex on the assessment of possible allergenicity. pp. 47-60], noting that no single factor is recognized as an identifier for protein allergenicity, suggested a weight of evidence approach be conducted that takes into account a variety of factors and approaches for an overall assessment of allergenic potential. These various recommendations are based on what is known about allergens, including the history of exposure and safety of the gene(s) source; amino acid sequence identity to human allergens; stability to pepsin digestion in vitro; protein abundance in the crop and processing effects; and when appropriate, specific IgE binding studies or skin-prick testing. Similarities and differences between these various suggested recommendations, as well as data gaps, are discussed. The US Environmental Protection Agency (EPA)'s Office of Research and Development (ORD) has initiated a targeted research effort to address data gaps and improve the various recommended methods/endpoints for assessing the allergenic risks associated with plant incorporated pesticides (PIPs) through both intramural and extramural (grant supported) research. The areas of primary focus for EPA include: (1) development and evaluation of animal models; (2) targeted or specific serological assays; and (3) structure-activity relationships. Details on the current as well as proposed EPA funded research are discussed. More recently US EPA has partnered with the National Institute of Allergy and Infectious Disease (NIAID), National Institutes of Health to support research in areas of mutual interest with respect to food allergy.