Effect of Heat Processing on IgE Reactivity and Cross‐Reactivity of Tropomyosin and Other Allergens of Asia‐Pacific Mollusc Species: Identification of Novel Sydney Rock Oyster Tropomyosin Sac g 1

Abstract

ScopeShellfish allergy is an increasing global health priority, frequently affecting adults. Molluscs are an important shellfish group causing food allergy but knowledge of their allergens and cross‐reactivity is limited. Optimal diagnosis of mollusc allergy enabling accurate advice on food avoidance is difficult. Allergens of four frequently ingested Asia‐Pacific molluscs are characterized: Sydney rock oyster (Saccostrea glomerata), blue mussel (Mytilus edulis), saucer scallop (Amusium balloti), and southern calamari (Sepioteuthis australis), examining cross‐reactivity between species and with blue swimmer crab tropomyosin, Por p 1.Methods and resultsIgE ELISA showed that cooking increased IgE reactivity of mollusc extracts and basophil activation confirmed biologically relevant IgE reactivity. Immunoblotting demonstrated strong IgE reactivity of several proteins including one corresponding to heat‐stable tropomyosin in all species (37–40 kDa). IgE‐reactive Sydney rock oyster proteins were identified by mass spectrometry, and the novel major oyster tropomyosin allergen was cloned, sequenced, and designated Sac g 1 by the IUIS. Oyster extracts showed highest IgE cross‐reactivity with other molluscs, while mussel cross‐reactivity was weakest. Inhibition immunoblotting demonstrated high cross‐reactivity between tropomyosins of mollusc and crustacean species.ConclusionThese findings inform novel approaches for reliable diagnosis and improved management of mollusc allergy.

Effects of Extraction Buffer on the Solubility and Immunoreactivity of the Pacific Oyster Allergens

“…Tropomyosin was also observed at the 50 kDa IgE-reactive spot with a high Mascot score and sequence coverage consistent with heat-induced degradation and aggregation. This higher molecular weight tropomyosin was also observed in other species including Sydney rock oyster [ 19 ] and Black tiger prawn [ 39 ]. In summary, each band contained between 2–4 known allergenic proteins, which could all contribute to the IgE reactivity.…”

“…Interestingly, paramyosin was also observed in the Carbonate-10 heated extracts. Furthermore, myosin heavy chain, a previously identified allergen in other molluscs [ 19 , 20 ], as well as filamin and troponin C, identified allergens in crustacean [ 21 , 22 ], were also detected. The other proteins including tubulin α-1C chain, α-actinin, spectrin-α chain, clathrin heavy chain, non-neuronal cytoplasmic intermediate filament protein and adipophilin were identified in the Pacific oyster IgE-reactive spots for the first time.…”

Clinical Management of Seafood Allergy

“…2,45 Cross-reactivity is shown to be more common among shellfish allergies (75%) [46][47][48][49] than among fish allergies (29%-67%). 45,46,[49][50][51][52][53] Therefore, it is essential to obtain a thorough history regarding complaints and symptoms with all other types of seafood that might serve as a clue to understand clinical cross-reactivity between and among fish and/or shellfish species (see Figure 2).…”

CytoBas: Precision component‐resolved diagnostics for allergy using flow cytometric staining of basophils with recombinant allergen tetramers

“… 2 While serum‐specific IgE detection is highly sensitive, the use of allergen extracts can yield positive results due to recognition by cross‐reactive antibodies of components that are not the drivers of disease. 3 , 4 , 5 , 6 , 7 , 8 …”