Tropomyosin Is the Major Mollusk Allergen: Reverse Transcriptase Polymerase Chain Reaction, Expression and IgE...

Area of Science:

• * Molecular biology and immunology.
• * Food allergy research.
• * Marine invertebrate genomics.

Background:

• * Shellfish allergies are a significant public health concern, often triggered by specific proteins.
• * Tropomyosin has been identified as a major allergen in crustaceans, but its role in mollusks requires further investigation.
• * Edible mollusks like abalone, scallops, and mussels are common sources of dietary exposure.

Purpose of the Study:

• * To investigate tropomyosin as a potential major allergen in three common edible mollusks: abalone, scallop, and mussel.
• * To compare the allergenic potential and sequence homology of mollusk tropomyosins with known crustacean allergens.
• * To assess the utility of tropomyosin gene sequences for phylogenetic analysis of mollusks.

Main Methods:

• * Complementary DNA (cDNA) amplification of tropomyosin genes from abalone, scallop, and mussel using reverse transcriptase polymerase chain reaction (RT-PCR).
• * Cloning of amplified cDNAs into plasmid vectors for protein expression.
• * Immunoblot analysis using serum IgE from shellfish-allergic and non-allergic individuals.
• * Absorption experiments to confirm IgE-binding specificity.
• * Sequence analysis (nucleotide and amino acid) and phylogenetic analysis using parsimony.

Main Results:

• * Recombinant mollusk tropomyosins showed specific IgE reactivity with sera from shellfish-allergic individuals, confirming their allergenic nature.
• * Mollusk tropomyosins share significant sequence similarity (>55%) with crustacean tropomyosins, known allergens.
• * Absorption experiments demonstrated that mollusk tropomyosins effectively removed IgE binding, identifying them as major allergens.
• * Sequence comparison suggested potential differences in allergenic epitopes between crustaceans and mollusks.
• * Nucleotide sequence analysis indicated tropomyosin as a valuable marker for mollusk phylogenetic studies.

Conclusions:

• * Tropomyosin is confirmed as the major allergen in common edible mollusks, responsible for IgE-mediated allergic reactions in shellfish-sensitive individuals.
• * While structurally similar to crustacean tropomyosins, molluscan tropomyosin epitopes may differ, influencing cross-reactivity.
• * The tropomyosin gene sequence serves as a robust tool for understanding evolutionary relationships within mollusks.