Analysis of the allergenicity and B cell epitopes in tropomyosin of shrimp (Litopenaeus vannamei) and correlation to cross-reactivity based on epitopes with fish (Larimichthys crocea) and clam (Ruditapes philippinarum).

Tropomyosin (TM) is a highly conserved protein that considered as the major allergen of crustacean and mollusk species, while, fish-TM also shares high homology with low allergenicity. In this study, the amino acid sequence, B cell epitopes and allergenicity of shrimp (Litopenaeus vannamei), which is widely consumed, were evaluated by using immunoinformatic tools, dot-blot, enzyme-linked immunosorbent assay (ELISA) and mediator release assay. Meanwhile, cross-reactivity of allergic epitopes of fish-TM, shrimp-TM and clam-TM were assessed. Results showed that three IgE-binding epitopes (X1: 47-61, QKRMQQLENDLDQVQ; X2: 97-108, EDLERSEERLNT and X3: 244-257, RSVQKLQKEVDRLE) of shrimp-TM also exhibited degranulation ability. In comparison with epitopes from shrimp-TM, those from clam-TM showed high cross-reactivity (>80%) and degranulation ability, while those from fish-TM showed low cross-reactivity (<20%). These findings would apply a new understanding of the cross-reactivity of TM from fish, shrimp and clam in terms of allergenic epitopes.