Food allergies affect ∼3.5-4.0% of the worldwide population. Immediate-type food allergies are mediated by the production of IgE antibodies to specific proteins that occur naturally in allergenic foods. Symptoms are individually variable ranging from mild rashes and hives to life-threatening anaphylactic shock. Seafood allergies are among the most common types of food allergies on a worldwide basis. Allergies to fish and crustacean shellfish are very common. Molluscan shellfish allergies are well known but do not appear to occur as frequently. Molluscan shellfish allergies have been documented to all classes of mollusks including gastropods (e.g., limpet, abalone), bivalves (e.g., clams, oysters, mussels), and cephalopods (e.g., squid, octopus). Tropomyosin, a major muscle protein, is the only well-recognized allergen in molluscan shellfish. The allergens in oyster (Cra g 1), abalone (Hal m 1), and squid (Tod p 1) have been identified as tropomyosin. Cross-reactivity to tropomyosin from other molluscan shellfish species has been observed with sera from patients allergic to oysters, suggesting that individuals with allergies to molluscan shellfish should avoid eating all species of molluscan shellfish. Cross-reactions with the related tropomyosin allergens in crustacean shellfish may also occur but this is less clearly defined. Occupational allergies have also been described in workers exposed to molluscan shellfish products by the respiratory and/or cutaneous routes. With food allergies, one man's food may truly be another man's poison. Individuals with food allergies react adversely to the ingestion of foods and food ingredients that most consumers can safely ingest (Taylor and Hefle, 2001). The allergens that provoke adverse reactions in susceptible individuals are naturally occurring proteins in the specific foods (Bush and Hefle, 1996). Molluscan shellfish, like virtually all foods that contain protein, can provoke allergic reactions in some individuals.
"Crustaceans, particularly shrimps, are highly allergenic foods that are responsible for food-induced reactions in both children and adults  . Despite its high prevalence, knowledge of the allergen profile of crustaceans is still limited. "
[Show abstract][Hide abstract] ABSTRACT: Scope:
Shrimp is a seafood consumed worldwide and the main cause of severe allergenic reactions to crustaceans. Seafood allergy has been related to mite sensitization, mainly mediated by tropomyosin, but other proteins could be involved. The aim of the study was to identify new shrimp allergens implicated in mite-seafood cross-reactivity (CR) in two different climate populations: dry and humid climates.
Methods and results:
Shrimp and mite IgE-binding profiles of patients from continental dry and humid climates were analyzed by immunoblotting, and the most frequently recognized Solenocera melantho shrimp proteins were identified by MS as α-actinin, β-actin, fructose biphosphate aldolase, arginine kinase, sarcoplasmic calcium-binding protein, and ubiquitin. Using inhibition immunoblot assays, we demonstrate that tropomyosin and ubiquitin were responsible for mite-seafood CR from both climates; but also α-actinin and arginine kinase are implicated in dry- and humid-climate populations, respectively. Reciprocal inhibition assays demonstrated that mites are the primary sensitizer in humid-climate, as shrimp is in continental dry-climate population.
Several new shrimp allergens have been identified and should be considered in the diagnosis and treatment of shrimp allergy and mite-seafood CR. Differences in mite-seafood CR were founded to be based on the climate.
"Since TM is a common allergen in both crustaceans and mollusks (Ishikawa et al., 1998a;b; Lopata et al., 1997; Miyazawa et al., 1996; Suma et al., 2007), other potent allergens such as myosin heavy chain (Martins et al., 2004), troponin, actine, hemocyanin (Juji et al., 1990; Koshte et al., 1989; Maeda et al., 1991), and amylase (Azofra & Lombardero, 2003) are reported also in molluscan shellfish. These allergens were identified and characterized in different species such as mussel, oyster, and could exist alone in crustaceans (Table 2) (Taylor, 2008). Some of these allergenic proteins are rapidly degraded within a short period of digestion time, while TM seems to be relatively resistant to acidic digestion (Huang et al., 2010; Liu et al., 2010; 2011). "
"So far, allergens of 34 to 38 kDa identified as tropomyosin have been established as the major allergens of a number of prawn, termed Pen i 1  , Pen a 1  and Met e 1  depending on the species used. In addition, tropomyosin has also been identified as the major allergen of other crustaceans   , mollusks      , house dust mites   and cockroaches   . "
[Show abstract][Hide abstract] ABSTRACT: To characterize the major allergens of Macrobrachium rosenbergii (giant freshwater prawn).
Raw and cooked extracts of the giant freshwater prawn were prepared. The IgE reactivity pattern was identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting technique with the sera of 20 skin prick test (SPT) positive patients. The major allergen identified was then characterized using the proteomics approach involving a combination of two-dimensional (2-DE) electrophoresis, mass spectrometry and bioinformatics tools.
SDS-PAGE of the raw extract showed 23 protein bands (15-250 kDa) but those ranging from 40 to 100 kDa were not found in the cooked extract. From immunoblotting experiments, raw and cooked extracts demonstrated 11 and 5 IgE-binding proteins, respectively, with a molecular mass ranging from 15 to 155 kDa. A heat-resistant 36 kDa protein was identified as the major allergen of both extracts. In addition, a 42 kDa heat-sensitive protein was shown to be a major allergen of the raw extract. The 2-DE gel fractionated the prawn proteins to more than 50 different protein spots. Of these, 10 spots showed specific IgE reactivity with patients' sera. Matrix assisted laser desorption/ionization-time of flight (MALDI-TOF) analysis led to identification of 2 important allergens, tropomyosin and arginine kinase.
It can be concluded that the availability of such allergens would help in component-based diagnosis and therapy of prawn allergies.
Asian Pacific Journal of Tropical Biomedicine 01/2012; 2(1):50-4. DOI:10.1016/S2221-1691(11)60189-5
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