Molecular Characterization of the Allergenic Arginine Kinase from the Edible Insect Hermetia illucens (Black Soldier Fly).

SCOPE: Arginine kinase (AK) is an important enzyme for energy metabolism of invertebrate cells by participating in the maintenance of constant levels of ATP. However, AK is also recognized as a major allergen in insects and crustaceans capable of cross-reactivity with sera of patients sensitized to orthologous proteins. In the perspective of introducing insects or their derivatives in the human diet in Western world, it is of primary importance to evaluate possible risks for allergic consumers. METHODS AND RESULTS: This work reports the identification and characterization of AK from Hermetia illucens commonly known as the black soldier fly, a promising insect for human consumption. To evaluate allergenicity of AK from H. illucens, putative linear and conformational epitopes are identified by bioinformatics analyses, and Dot-Blot assays are carried out by using sera of patients allergic to shrimp or mites to validate the cross-reactivity. Gastrointestinal digestion reduces significantly the linear epitopes resulting in lower allergenicity, while the secondary structure is altered at increasing temperatures supporting the possible loss or reduction of conformational epitopes. CONCLUSION: The results indicate that the possible allergenicity of AK should be taken in consideration when dealing with novel foods containing H. illucens or its derivatives.

Allergens from Edible Insects: Cross-reactivity and Effects of Processing.

PURPOSE OF REVIEW: The recent introduction of edible insects in Western countries has raised concerns about their safety in terms of allergenic reactions. The characterization of insect allergens, the sensitization and cross-reactivity mechanisms, and the effects of food processing represent crucial information for risk assessment. RECENT FINDINGS: Allergic reactions to different insects and cross-reactivity with crustacean and inhalant allergens have been described, with the identification of new IgE-binding proteins besides well-known pan-allergens. Depending on the route of sensitization, different potential allergens seem to be involved. Food processing may affect the solubility and the immunoreactivity of insect allergens, with results depending on species and type of proteins. Chemical/enzymatic hydrolysis, in some cases, abolishes immunoreactivity. More studies based on subjects with a confirmed insect allergy are necessary to identify major and minor allergens and the role of the route of sensitization. The effects of processing need to be further investigated to assess the risk associated with the ingestion of insect-containing food products.

Effect of heat, enzymatic hydrolysis and acid-alkali treatment on the allergenicity of silkworm pupa protein extract.

Silkworm pupae are edible insects with high-quality nutrition in many Asian countries, but consumption of silkworm pupae can cause severe IgE-mediated allergic disease. The aim of this study was to investigate the effect of heat, enzymatic hydrolysis and acid-alkali treatment on the allergenicity of silkworm pupa protein extract (SPPE). Heating reduced the allergenicity of SPPE when the temperature was higher than 60 °C. Spectroscopy studies suggested an unfolded conformation of SPPE with heating, dependent on temperature and time. Enzymatic hydrolysis revealed that SPPE at 25 to 33 kDa contained pepsin- and trypsin-resistant allergens. The results of acid-alkali treatment suggested that low pH can promote hydrolysis of SPPE and decrease its allergenicity. Thus, heat, enzymatic hydrolysis and acid-alkali treatment can significantly decrease the allergenicity of SPPE, with heat-, enzyme- and acid-alkali-resistant allergens at 25 to 33 kDa SPPE. This study can help in the development of methods to prepare silkworm pupa protein.

Shellfish Tropomyosin IgE Cross-Reactivity Differs Among Edible Insect Species.

SCOPE: Insects are a potentially environmentally friendly alternative dietary protein source to supplement mammalian and fish sources, but potential allergenic risks are a concern. Consumption of insects may result in anaphylaxis and has been implicated in cross-reactivity with shellfish. Many allergenic proteins may be involved in cross-reactivity, including tropomyosin (TM). The uniformity of TM cross-reactivity among edible insects is unknown. Candidate edible insects for variability in shellfish IgE cross-reactivity are investigated. METHODS AND RESULTS: Selected insects and known related sources of allergens are extracted and probed by immunoblot with sera/plasma from patients sensitized to insects or shellfish. Quantification of TM in these extracts is performed using mass spectrometry. A comparison of the quantity of TM and the IgE reactivity of TM from these insects is performed. Distinct patterns of IgE cross-reactivity are observed with three insect species showing diminished reactivity. This pattern is not consistent with the amount of TM present in these insects, or with overall sequence homology. CONCLUSION: Insects display a diversity of TM-associated IgE reactivity. It is likely that minor sequence features and/or structural effects are primarily responsible. Additionally, it is demonstrated that some insect species may present significantly less IgE cross-reactivity to shrimp than do others.

Prevalence and cluster effect of self-reported allergic reactions among insect consumers.

BACKGROUND: Entomophagy is a common practice in many parts of the world. Allergic symptoms after insect consumption have been reported in healthcare literature and in the news. OBJECTIVE: We evaluated prevalence and association of allergic history and self-reported allergic reactions after entomophagy. METHODS: We conducted a cross sectional internet-based survey. Participants were people who have consumed insects. Collected information included demographic data, the practice of entomophagy, allergic history and self-reported allergic symptoms. RESULTS: During May to October 2017, 140 people completed the survey. Median and range of age are 27 and 18-64 years. Ninety-two (65.7%) were female. Thirty-seven (26.4%) and 13 (9.3%) participants had history of allergy and seafood allergy, respectively. Eighteen (12.9%; 95% confidence intervals (CI) 7.3-18.4) participants reported allergic reactions after insect consumption. Nine symptomatic participants reported other people who partook insects to have allergic symptoms. Reported factors with significant association with allergic reactions were history of allergy and seafood allergy with prevalence ratios of 4.83 (CI 1.83-10.44) and 3.76 (CI 1.59-8.87), respectively. CONCLUSIONS: The prevalence of self-reported allergic reactions after entomophagy is 12.9%. Clusters of people with post-entomophagy allergic symptoms are found. History of allergy and seafood allergy are associated with post-entomophagy allergic reactions.

Insect Allergens on the Dining Table.

Edible insects are important sources of nutrition, particularly in Africa, Asia, and Latin America. Recently, edible insects have gained considerable interest as a possible solution to global exhaustion of the food supply with population growth. However, little attention has been given to the adverse reactions caused by insect consumption. Here, we provide an overview of the food allergens in edible insects and offer insights for further studies. Most of the edible insect allergens identified to date are highly cross-reactive invertebrate pan-allergens such as tropomyosin and arginine kinase. Allergic reactions to these allergens may be cross-reactions resulting from sensitization to shellfish and/or house dust mites. No unique insect allergen specifically eliciting a food allergy has been described. Many of the edible insect allergens described thus far have counterpart allergens in cockroaches, which are an important cause of respiratory allergies, but it is questionable whether inhalant allergens can cause food allergies. Greater effort is needed to characterize the allergens that are unique to edible insects so that safe edible insects can be developed. The changes in insect proteins upon food processing or cooking should also be examined to enhance our understanding of edible insect food allergies.