Nakamura, R; Matsuda, T

Bioscience, Biotechnology, and Biochemistry [BIOSCI., BIOTECHNOL., BIOCHEM.], vol. 60, no. 8, pp. 1215-1221, Aug 1996

Allergenic proteins with a molecular mass of about 14 to 16 kDa were isolated from a rice salt-soluble fraction based on the reactivity with IgE antibodies from patients allergic to rice. cDNA clones encoding these allergenic proteins were isolated from a cDNA library of maturing rice seeds, and the deduced amino acid sequences showed considerable similarity to wheat and barley alpha -amylase/trypsin inhibitors, which have recently been identified as major allergens associated with baker's asthma. An antisense RNA strategy was applied to repress the allergen gene expression in maturing rice seeds. Immunoblotting and ELISA analyses of the seeds using a monoclonal antibody to a 16-kDa allergen showed that allergen content of seeds from several transgenic rice plants was markedly lower than that of the seeds from parental wild type rice.

Nordlee, JA; Taylor, SL; Townsend, JA; Thomas, LA; Bush, RK

New England Journal of Medicine [N. ENGL. J. MED.], vol. 334, no. 11, pp. 688-692, 1996

The nutritional quality of soybeans (Glycine max) is compromised by a relative deficiency of methionine in the protein fraction of the seeds. To improve the nutritional quality, methionine-rich 2S albumin from the Brazil nut (Bertholletia excelsa) has been introduced into transgenic soybeans. Since the Brazil nut is a known allergenic food, we assessed the allergenicity of the 2S albumin. The ability of proteins in transgenic and nontransgenic soybeans, Brazil nuts, and purified 2S albumin to bind to IgE in serum from subjects allergic to Brazil nuts was determined by radioallergosorbent tests (four subjects) and sodium dodecyl sulfate-polyacrylamide-gel electrophoresis (nine subjects) with immunoblotting and autoradiography. Three subjects also underwent skin-prick testing with extracts of soybean, transgenic soybean, and Brazil nut. On radioallergosorbent testing of pooled serum from four subjects allergic to Brazil nuts, protein extracts of transgenic soybean inhibited binding of IgE to Brazil-nut proteins. On immunoblotting, serum IgE from eight of nine subjects bound to purified 2S albumin from the Brazil nut and to proteins of similar molecular weight in the Brazil nut and the transgenic soybean. On skin-prick testing, three subjects had positive reactions to extracts of Brazil nut and transgenic soybean and negative reactions to soybean extract. The 2S albumin is probably a major Brazil-nut allergen, and the transgenic soybeans analyzed in this study contain this protein. Our study shows that an allergen from a food known to be allergenic can be transferred into another food by genetic engineering.

Burks, AW; Fuchs, RL

Journal of Allergy and Clinical Immunology [J. ALLERGY CLIN. IMMUNOL.], vol. 96, no. 6 pt 1, pp. 1008-1010, 1995

A gene has been introduced into soybeans to confer tolerance to glyphosate, the active ingredient in the herbicide, Roundup (Monsanto Co., St. Louis, Mo.) Soybean varieties expressing this trait will enable farmers to use Roundup herbicide within the crop during the growing season. Previous studies have confirmed the safety of the introduced protein (5-enolpyruvylshikimate-3-phosphate synthase [EPSPS]), which confers glyphosate tolerance. Over 1400 analyses have confirmed the compositional and nutritional equivalence of the soybeans produced from the glyphosate-tolerant soybean variety to the parental soybean variety. The multiple, endogenous protein allergens previously identified in soybeans represent an additional safety concern. The purpose of this study was to qualitatively and quantitatively compare the endogenous allergens in glyphosate-tolerant and commercial soybean varieties and to determine whether the genetic engineering process itself affected these components.

Lehrer, SB; Reese, G

ALLERGY - A DISEASE OF MODERN SOCIETY, 1997, pp. 122-124, International Archives of Allergy and Immunology, vol. 113, no. 1-3

A number of agricultural crops are being modified for various purposes using recombinant DNA technology. Since transferred genes may code for proteins that are ordinarily not present, there is concern about the potential allergenicity of these new varieties. The safety evaluation of transgenic foods is relatively easy when the allergenicity of the gene source is known. Recombinant allergens in genetically engineered or altered foods can be identified using traditional immunological assays such as RAST or ELISA inhibition or immunoblotting procedures. Our recent studies of two corn proteins (10 kD and HSZ) used to alter grain amino acid composition and of transgenic soybeans with an altered fatty acid profile are examples of this approach. Both 10 kD and HSZ did not bind IgE antibodies from sera of corn-reactive subjects by immunoblotting. Studies of wild-type and transgenic soybeans with high oleic acidic content by RAST inhibition and immunoblotting with pooled sera of soy-allergic individuals demonstrated no difference in the allergen content of both extracts. In contrast to these studies, a recent investigation by Nordlee et al. (1996) of transgenic soybeans which expressed a methionine/cysteine-rich protein from Brazil nuts identified this protein as a major Brazil nut allergen. These studies indicate that, when the gene source is from a known allergen or if the recipient contains allergens, it is possible to determine whether the allergen content of the transgenic line is altered relative to the nontransgenic varieties.

Astwood, JD; Leach, JN; Fuchs, RL*

Nature Biotechnology [NAT. BIOTECHNOL.], vol. 14, no. 10, pp. 1269-1273, 1996

An integral part of the safety assessment of genetically modified plants is consideration of possible human health effects, especially food allergy. Prospective testing for allergenicity of proteins obtained from sources with no prior history of causing allergy has been difficult because of the absence of valid methods and models. Food allergens may share physicochemical properties that distinguish them from nonallergens, properties that may be used as a tool to predict the inherent allergenicity of proteins newly introduced into the food supply by genetic engineering. One candidate property is stability to digestion. We have systematically evaluated the stability of food allergens that are active via the gastrointestinal tract in a simple model of gastric digestion, emphasizing the major allergens of plant-derived foods such as legumes (peanuts and soybean). Important food allergens were stable to digestion in the gastric model (simulated gastric fluid). For example, soybean beta -conglycinin was stable for 60 min. In contrast, nonallergenic food proteins, such as spinach ribulose bis-phosphate carboxylase/oxygenase, were digested in simulated gastric fluid within 15 sec. The data are consistent with the hypothesis that food allergens must exhibit sufficient gastric stability to reach the intestinal mucosa where absorption and sensitization (development of atopy) can occur. Thus, the stability to digestion is a significant and valid parameter that distinguishes food allergens from nonallergens.