Noormalin Abdullah

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.

Production of Allergen Extracts for Bivalve Allergy Diagnosis Using Skin PrickTest

Background: Whilst the consumption of bivalves is reasonably high in Malaysia, the frequency of allergy to this group of shellfish in the local population is largely unknown. The aim of this preliminary study was to produce bivalve allergen extracts and to investigate the frequency of bivalve sensitization among the local atopic population. Methods: Raw allergen extracts were prepared from 5 different species of bivalves. Their protein profiles were studied using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Results: In SDS-PAGE, the bivalve extracts demonstrated 10 to 23 protein bands. The five protein profiles varied considerably but most visible protein bands lay within 25-100 kDa. At the same time, fifty patients with a history of atopy were skin prick tested (SPT) with these raw extracts of bivalves. Of the 50 subjects, 13 (26%) had a positive SPT to at least one of the 5 bivalve extracts tested, 8 (61%) reacted to one bivalve extract while only one (8%) reacted to all 5 bivalve extracts. The frequency of skin test reactivity to Malaysian cockle was the highest at 22%, followed by Carpet clam, 12% and 4% to the other 3 bivalve extracts; Tropical oyster, Asian clam and Asian green mussel. Conclusion: This study showed that of the five different bivalve species, cockle was found to have the highest frequency in skin test reactivity. It appears that an individual, who is sensitized to a mite, is also likely to be sensitized to bivalves.