Tropomyosin and Actin Identified as Major Allergens of the Carpet Clam (Paphia textile) and the Effect of Cooking on Their Allergenicity.

Objectives: To identify the major allergenic proteins of clam (Paphia textile) and to investigate the effect of different cooking methods on the allergenicity of these identified proteins.

Methods: Clam protein extracts were separated by denaturing polyacrylamide gel electrophoresis. IgE reactive proteins were then analyzed by immunoblotting with sera from patients with positive skin prick tests (SPT) to the raw clam extract. Mass spectrometry was used to identify the major allergenic proteins of this clam.

Results: Raw extract showed 12 protein bands (18-150 kDa). In contrast, fewer protein bands were seen in the boiled extract; those ranging from 40 to 150 kDa were denatured. The protein profiles were similarly altered by frying or roasting. The immunoblots of raw and boiled extracts yielded 10 and 2 IgE-binding proteins, respectively. The fried and roasted extracts showed only a single IgE-binding protein at 37 kDa. Mass spectrometry analysis of the 37 and 42 kDa major allergens indicated that these spots were tropomyosin and actin, respectively.

Conclusion: The two major allergens of Paphia textile were identified as the thermostable tropomyosin and a new thermolabile allergen actin.