Molecular characteristics of major and minor allergens in crustaceans

Introduction: The growing international trade in seafood species and products has added to the increased frequency of processing of a variety of seafood products across many countries and associated allergic reactions in workers and consumers. The major crustacean allergen is tropomyosin, although other allergens such as arginine kinase, myosin light chain and proteases may play an important role in these reactions.  

Objectives: To identify, characterise and compare IgE binding proteins between fresh and heat processed lobsters and prawns.  

Methods: Proteins extracts were generated from 2 Rock lobsters (Jasus lalandii; J. edwardsii), one slipper lobster (Thenus orientalis) and the Tiger - (Penaeus monodon) and King prawn (Melicertus latisulcatus). IgE binding proteins were indentified by SDS gel-electrophoresis and immunoblotting. Protease activity was established and characterized using zymography and specific inhibitors. Allergens were purified by chromatography and sequenced using molecular techniques. Recombinant allergens from some major allergens were generated in E. coli and characterized for their immunoreactivity.  Results: The major allergens tropomyosin and arginine kinase were identified in all analyzed species. Several tropomyosin isoforms were characterized in the lobsters and prawns. Thermal processing of prawns increased the IgE binding reactivity to several proteins in the Tiger prawn but not in the King prawn. Serine and cysteine protease activity was demonstrated in the gut but also in the tissue of prawns and lobsters.  

Conclusions: Thermal processing of major and minor allergens can have very different effects on both their abundance and molecular structure. This directly affects the specificity of tests for allergen detection in the environment and accuracy of diagnosing sensitisation. The increased repertoire of newly identified allergens using proteomic techniques and biotechnological production of allergens will improve the component resolved diagnosis of occupational sensitisation to shellfish. Improved reagent composition will contribute towards optimising clinical diagnosis, exposure characterisation and managing shellfish allergy.