The europrevall allergen library: high quality purified natural and recombinant allergens from nuts and seeds including walnut, sesame, soybean, mustard and wheat for in vitro diagnosis

Background: The quality of in vitro IgE tests used for food allergy diagnosis mainly depends on the analytes used. Recently, within the EC funded IP Europrevall a library of 31 highly purified allergens from 10 foods listed in the new Labelling directive of the European Commission was established for developing novel diagnostics. As a follow up, preparation of 11 allergens from nuts, seeds and grains (also included in the EC Labelling directive) was performed accordingly. Methods: Allergens from walnut, sesame seeds, soybean, mustard and wheat were purified from natural sources including 2S albumins, 7S seed storage globulins and LTP according to recently established purification protocols. In addition a Bet v 1 homologue from soybean and profilin from wheat were produced as recombinant allergens. Subsequently the highly pure protein batches were characterized regarding their structural integrity, biological and allergenic activity. Protein mass was verified by mass spectrometry and sequence integrity by MALDI-TOF and N-terminal sequencing. Secondary structure was evaluated by NMR maps of low molecular weight proteins. Allergenic activity was characterized using a panel of sera from food allergic patients. Results and Conclusions: Recently established purification protocols for natural and recombinant allergens were adopted for each allergen and quality assessment of the purified batches was performed. Depending on either natural or recombinant origin different quality criteria were defined and met for inclusion into the allergen library. Structural integrity of the purified proteins was verified and IgE binding activity was assessed. The harmonised purification and characterisation of food allergens will help to identify the prevalence of IgE reactivity of each allergen and to discriminate between major and minor allergens within the European food allergic population. This study was supported by the EC-project EuroPrevall, FOOD-CT-2005-514000.