Investigations of immunogenic, allergenic and adjuvant properties of Cry1Ab protein after intragastric exposure in a food allergy model in mice
Andreassen, Monica; Bøhn, Thomas; Wikmark, Odd-Gunnar; Bodin, Johanna; Traavik, Terje; Løvik, Martinus; Nygaard, Unni Cecilie
Abstract
Background: In genetically modified (GM) crops there is a risk that the inserted genes may introduce new
allergens and/or adjuvants into the food and feed chain. The MON810 maize, expressing the insecticidal
Cry1Ab toxin, is grown in many countries worldwide. In animal models, intranasal and intraperitoneal immunisations
with the purified Cry1Ab proteins have induced immune responses, and feeding trials with Cry1Ab-containing feed
have revealed some altered immune responses. Previous investigations have primarily measured antibody responses
to the protein, while investigations of clinical food allergy symptoms, or allergy promotion (adjuvant effect) associated
with the Cry1Ab protein are largely missing. We aimed to investigate immunogenic, allergenic and adjuvant properties
of purified Cry1Ab toxin (trypCry1Ab, i.e., trypsin activated Cry1Ab) in a mouse model of food allergy.
Method: Female C3H/HeJ mice were immunized by intragastric gavage of 10 μg purified, trypsin activated Cry1Ab toxin
(trypCry1Ab) alone or together with the food allergen lupin. Cholera toxin was added as a positive control for adjuvant
effect to break oral tolerance. Clinical symptoms (anaphylaxis) as well as humoral and cellular responses were assessed.
Results: In contrast to results from previous airway investigations, we observed no indication of immunogenic
properties of trypCry1Ab protein after repeated intragastric exposures to one dose, with or without CT as
adjuvant. Moreover, the results indicated that trypCry1Ab given by the intragastric route was not able to promote
allergic responses or anaphylactic reactions against the co-administered allergen lupin at the given dose.
Conclusion: The study suggests no immunogenic, allergenic or adjuvant capacity of the given dose of trypCry1Ab
protein after intragastric exposure of prime aged mice.