Allergen Databases Research Articles

IgE-Mediated Cannabis Allergy and Cross-Reactivity Syndromes: A Roadmap for Correct Diagnosis and Management.

With increased access and decriminalization of cannabis use, cases of IgE-dependent cannabis allergy (CA) and cross-reactivity syndromes have been increasingly reported. However, the exact prevalence of cannabis allergy and associated cross-reactive food syndromes (CAFS) remains unknown and is likely to be underestimated due to a lack of awareness and insufficient knowledge of the subject among health care professionals. Therefore, this practical roadmap aims to familiarize the reader with the early recognition and correct management of IgE-dependent cannabis-related allergies. In order to understand the mechanisms underlying these cross-reactivity syndromes and to enable personalized diagnosis and management, special attention is given to the molecular diagnosis of cannabis-related allergies. The predominant signs and symptoms of CA are rhinoconjunctivitis and contact urticaria/angioedema. However, CA can also present as a life-threatening condition. In addition, many patients with CA also have distinct cross-reactivity syndromes, mainly involving fruits, vegetables, nuts and cereals. At present, five allergenic components of Cannabis sativa (Can s); Can s 2 (profilin), Can s 3 (a non-specific lipid protein), Can s 4 (oxygen-evolving enhancer protein 2 oxygen), Can s 5 (the Bet v 1 homologue) and Can s 7 (thaumatin-like protein) have been characterized and indexed in the WHO International Union of Immunological Sciences (IUIS) allergen database. However, neither of them is currently readily available for diagnosis, which generally starts by testing crude extracts of native allergens. The road to a clear understanding of CA and the associated cross-reactive food syndromes (CAFS) is still long and winding, but well worth further exploration.

Fecal IgE Analyses Reveal a Role for Stratifying Peanut-Allergic Patients.

Peanut allergy (PA) is an IgE-mediated food allergy with variable clinical outcomes. Mild-to-severe symptoms affect various organs and, often, the gastrointestinal tract. The role of intestine-derived IgE antibodies in astrointestinal PA symptoms is poorly understood. This study aimed to examine fecal IgE responses in PA as a novel approach to patient endotyping. Feces and serum samples were collected from peanut-allergic and healthy children (n=26) to identify IgE and cytokines using multiplex assays. Shotgun metagenomics DNA sequencing and allergen database comparisons made it possible to identify microbial peptides with homology to known allergens. Compared to controls, fecal IgE signatures showed broad diversity and increased levels for 13 allergens, including food, venom, contact, and respiratory allergens (P<.01-.0001). Overall, fecal IgE patterns were negatively correlated compared to sera IgE patterns in PA patients, with the greatest differences recorded for peanut allergens (P<.0001). For 83% of the allergens recognized by fecal IgE, we found bacterial homologs from PA patients' gut microbiome (eg, thaumatin-like protein Acinetobacter baumannii vs Act d 2, 109/124 aa identical). Compared to controls, PA patients had higher levels of fecal IgA, IL-22, and auto-IgE binding to their own fecal proteins (P<.001). Finally, levels of fecal IgE correlated with abdominal pain scores (P<.0001), suggesting a link between local IgE production and clinical outcomes. Fecal IgE release from the intestinal mucosa could be an underlying mechanism of severe abdominal pain through the association between leaky gut epithelia and anticommensal TH2 responses in PA.

Linear epitopes of bony fish β-parvalbumins.

Fish β-parvalbumins are common targets of allergy-causing immunity. The nature of antibody responses to such allergens determines the biological outcome following exposure to fish. Specific epitopes on these allergens recognised by antibodies are incompletely characterised. High-content peptide microarrays offer a solution to the identification of linear epitopes recognised by antibodies. We characterized IgG and IgG4 recognition of linear epitopes of fish β-parvalbumins defined in the WHO/IUIS allergen database as such responses hold the potential to counter an allergic reaction to these allergens. Peripheral blood samples, collected over three years, of 15 atopic but not fish-allergic subjects were investigated using a microarray platform that carried every possible 16-mer peptide of known isoforms and isoallergens of these and other allergens. Interindividual differences in epitope recognition patterns were observed. In contrast, reactivity patterns in a given individual were by comparison more stable during the 3 years-course of the study. Nevertheless, evidence of the induction of novel specificities over time was identified across multiple regions of the allergens. Particularly reactive epitopes were identified in the D helix of Cyp c 1 and in the C-terminus of Gad c 1 and Gad m 1.02. Residues important for the recognition of certain linear epitopes were identified. Patterns of differential recognition of isoallergens were observed in some subjects. Altogether, comprehensive analysis of antibody recognition of linear epitopes of multiple allergens enables characterisation of the nature of the antibody responses targeting this important set of food allergens.

IgE Antibody Assay-Based Allergen Database(CLSI-IL/A-37)

There are 8 established allergen databases (IUIS/WHO ANDB, Allergome, AllFam, AllergenOnline, SDAP, COMPARE, IEDB and AllerBase).None of these provide a comprehensive listing of the internationally-accepted nomenclature codes and Linnean system descriptors of the~1000 extract and molecular allergens used world-wide in diagnostic single-and multi-plex IgE antibody assays. The new Diagnostic Allergen DataBase (DADB) has been prepared by an international scientific committee of the Clinical and Laboratory Standards Institute to specifically provide these data together in a readily-searchable Excel database. Using peanut as an example, the DADB lists the allergens’ unique assay working codes (F13), general category (food), principal IgE antibody assay method(s) where the allergen specificity is available, common name (peanut), taxonomical name (Arachis hypogaea), and the NCBI, NPU, LOINC, Allergome and IUIS/WHO descriptor codes for allergens and their assays. The DADB benefits manufacturers of allergen-specific IgE assays by providing unambiguous specificity descriptors. With the DADB, allergen extract manufacturers will have clearly defined specificity targets for allergenic product development. Government regulators will have clarity on the specificity of new allergen reagents that are being submitted for clearance. IgE antibody proficiency testing programs (e.g. CAP) will be able to clearly define the IgE antibody specificities being measured in their challenge sera. The clinician will precisely know the allergen specificity of IgE antibody that is measured in their reference laboratory. Finally, the allergic patient will be assured that their allergic sensitization is being assessed in an assay with a well-characterized allergen reagent.

Updates on Databases of Allergens and Allergen-Epitopes.

The increasing prevalence of allergic diseases is of great public health concern. Environmental and food allergens are the major triggers of allergic diseases via respiratory or gastrointestinal routes, respectively. A major setback in the clinical management of allergies is the unavailability of purified allergens required for diagnostic purposes. Furthermore, manipulation of allergen sequences and structures by employing protein-engineering approaches is neededto design immunotherapeutic vaccines. All these approaches rely upon the sequence, structure, and epitope location of allergens. A number of databases have therefore been developed that serve as repositories of molecular information of allergens. In this chapter, we discuss the five most important widely used allergen databases that might be helpful for the research community working on molecular allergology.

Formulating preservatives to enhance stability of crude extracts of food allergens used for food allergy management and immunotherapy

&lt;abstract&gt; &lt;p&gt;Due to rapid degradation of food allergenic extracts, devising some optimal conditions is mandatory to boost shelf life of extracts for appropriate diagnosis of allergy and immunotherapy. In the current study, food extracts of &lt;italic&gt;Bos domesticus&lt;/italic&gt; (cow) milk, &lt;italic&gt;Gallus domesticus&lt;/italic&gt; (chicken) egg, &lt;italic&gt;Trititcum aestivum&lt;/italic&gt; (wheat), &lt;italic&gt;Gallus domesticus&lt;/italic&gt; (chicken) meat and &lt;italic&gt;Arachis hypogaea&lt;/italic&gt; (peanut) were prepared and their protein estimation was evaluated by bicinchoninic acid (BCA) method. Stability of food extracts was evaluated under two groups of preservatives; storage with coca's solution (mixture of sodium chloride (NaCl) and sodium bicarbonate (NaHCO&lt;sub&gt;3&lt;/sub&gt;)) and stabilizing buffer (sucrose and ethylene diamine tetra-acetic acid (EDTA)). Effect of cocktail of protease inhibitors ((phenyl methyl sulfonyl fluoride (PMSF) and dithiothreitol (DTT)) and glycerol was checked on food extracts under both groups of preservatives. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS PAGE) was performed for food protein extracts after 1, 3 and 6 months under both conditions. Size of obtained protein bands were compared with allergen database (&lt;ext-link ext-link-type="uri" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.allergen.org"&gt;http://www.allergen.org&lt;/ext-link&gt;) in order to check their potential allergenicity. Extracts stored with coca's solution remained more potent as compared to stabilizing buffer for up to 3 months except &lt;italic&gt;Gallus domesticus&lt;/italic&gt; egg, whose proteins remained more potent in stabilizing buffer as compared to coca's solution. Most of the proteins deteriorated at 6 months of storage. Glycerol had shown better results under both conditions. A formulation containing a combination of coca's solution along with cocktail of protease inhibitors and glycerol improved the shelf life of food extracts for up to 3 months, showing better potential for stabilization of allergenic food extracts and their use for immunotherapy.&lt;/p&gt; &lt;/abstract&gt;

Allergenic food protein consumption is associated with systemic IgG antibody responses in non-allergic individuals

Although food-directed immunoglobulin E (IgE) has been studied in the context of allergies, the prevalence and magnitude of IgG responses against dietary antigens are incompletely characterized in the general population. Here, we measured IgG binding against food and environmental antigens obtained from allergen databases and the immune epitope database (IEDB), represented in a phage displayed library of 58,233 peptides. By profiling blood samples of a large cohort representing the average adult Israeli population (n= 1,003), we showed that many food antigens elicited systemic IgG in up to 50% of individuals. Dietary intake of specific food protein correlated with antibody binding, suggesting that diet can shape the IgG epitope repertoire. Our work documents abundant systemic IgG responses against food antigens and provides a reference map of the exact immunogenic epitopes on a population scale, laying the foundation to unravel the role of food- and environmental antigen-directed antibody binding in disease contexts.

Biochemical and clinical studies of putative allergens to assess what distinguishes them from other non-allergenic proteins in the same family

Many protein families have numerous members listed in databases as allergens; however, some allergen database entries, herein called “orphan allergens”, are members of large families of which all other members are not allergens. These orphan allergens provide an opportunity to assess whether specific structural features render a protein allergenic. Three orphan allergens [Cladosporium herbarum aldehyde dehydrogenase (ChALDH), Alternaria alternata ALDH (AaALDH), and C. herbarum mannitol dehydrogenase (ChMDH)] were recombinantly produced and purified for structure characterization and for clinical skin prick testing (SPT) in mold allergic participants. Examination of the X-ray crystal structures of ChALDH and ChMDH and a homology structure model of AaALDH did not identify any discernable epitopes that distinguish these putative orphan allergens from their non-allergenic protein relatives. SPT results were aligned with ChMDH being an allergen, 53% of the participants were SPT (+). AaALDH did not elicit SPT reactivity above control proteins not in allergen databases (i.e., Psedomonas syringae indole-3-acetaldehyde dehydrogenase and Zea mays ALDH). Although published results showed consequential human IgE reactivity with ChALDH, no SPT reactivity was observed in this study. With only one of these three orphan allergens, ChMDH, eliciting SPT(+) reactions consistent with the protein being included in allergen databases, this underscores the complicated nature of how bioinformatics is used to assess the potential allergenicity of food proteins that could be newly added to human diets and, when needed, the subsequent clinical testing of that bioinformatic assessment.Trial registration number and date of registration AAC-2017-0467, approved as WIRB protocol #20172536 on 07DEC2017 by WIRB-Copernicus (OHRP/FDA Registration #: IRB00000533, organization #: IORG0000432).

Les bases de données en allergologie moléculaire

The growing number of characterized allergen molecules and their use in clinical diagnosis has led to the creation of several allergen databases fulfilling different needs. Those range from systematic allergen nomenclature to clinical diagnosis, including comparison of biochemical properties and immunological and structural characterization. The databases listed in this brief summary have overlapping features and their individual utility will depend on the needs of the user.

Comprehensive COMPARE database reduces allergenic risk of novel food proteins

ABSTRACT The comprehensiveness of the allergen database used to bioinformatically compare a novel food protein with known allergens is critical to the ability to assess the allergenic risk of newly expressed proteins in genetically engineered crops. The strength of the relationship between a candidate GE protein’s amino acid sequence and that of known allergens is used to predict cross-reactive risk. The number of truly novel allergen sequences added annually to the COMPARE database reflects on the comprehensiveness of our knowledge of allergen amino acid sequence diversity. Here, we investigated the most recent five years of updates to the COMPARE allergen database for truly novel entries. Results indicate that few truly novel sequences are added each year, suggesting that the database and our knowledge of allergen sequence diversity is currently quite comprehensive, and that current in silico prediction of allergenic risk for novel food proteins is robust.

Comparison of salt-soluble wheat allergens in a mouse model vs. known human wheat allergens: evidence from durum and ancient wheats

Abstract Wheat allergies are among the major types of food allergies that are potentially life-threatening because of anaphylaxis. Monitoring changes to wheat allergens in novel wheat lines/genotypes is critical to prevent inadvertent introduction of potentially hyper-allergenic varieties from genetic modification. Nonetheless, validated methods for this purpose are unavailable at present. We have previously described a mouse model of wheat allergy using salt-soluble protein extract (SSPE) from durum wheat. As a proof-of-concept study, here we tested the hypothesis that wheat allergens in this mouse model will be identical to those reported for human wheat allergy. We created a mini plasma bank using hyper-IgE immune plasma obtained from Balb/cJ female mice (n=20) that had been sensitized with durum-SSPE along with alum adjuvant followed by repeated booster intraperitoneal injections with SSPE alone. Using hyper-IgE plasma we optimized an IgE-Western Blot (IgEWB) method to identify allergens present in SSPEs from durum wheat and an ancient tauschii wheat. The IgE-binding allergenic bands present in raw and boiled/reduced SSPEs from durum and tauschii wheats were sequenced using LC-MS/MS method. The most abundant allergens were identified and compared with a human wheat allergen database. There were 13 allergens present in durum-SSPE, of which 6 were present only in raw extract, 2 were present only in boiled/reduced extract, and 5 were present in both. There were 10 allergens present in tauschii-SSPE, of which 7 were present only in raw extract, and 3 were present in both raw and boiled/reduced extract. Between durum and tauschii wheats, 14 allergens were present in this mouse model, of which 10 are human wheat allergens. Supported by USDA/NIFA, MSU

A new paradigm to search for allergenic proteins in novel foods by integrating proteomics analysis and in silico sequence homology prediction: Focus on spirulina and chlorella microalgae.

Since novel nutrient sources with high protein content, such as yeast, fungi, bacteria, algae, and insects, are increasingly introduced in the consumer market, safety evaluation studies on their potentially allergenic proteins are required. A pipeline for in silico establishing the sequence-based homology between proteins of spirulina (Arthrospira platensis) and chlorella (Chlorella vulgaris) micro-algae and those included in the AllergenOnline (AO) database (AllergenOnline.org) is described. The extracted proteins were first identified through tryptic peptides analysis by reversed-phase liquid chromatography and high resolution/accuracy Fourier-transform tandem mass spectrometry (RPLC-ESI-FTMS/MS), followed by a quest on the UniProt database. The AO database was subsequently interrogated to assess sequence similarity between identified microalgal proteins and known allergens, based on criteria established by the World Health Organization (WHO) and Food and Agriculture Organization (FAO). A direct search for microalgal proteins already included in allergen databases was also performed using the Allergome database. Six proteins exhibiting a significant homology with food allergens were identified in spirulina extracts. Five of them, i.e., two thioredoxins (D4ZSU6, K1VP15), a superoxide dismutase (C3V3P3), a glyceraldehyde-3-phosphate dehydrogenase (K1W168), and a triosephosphate isomerase (D5A635), resulted from the search on AO. The sixth protein, C-phycocyanin beta subunit (P72508), was directly obtained after examining the Allergome database. Two proteins exhibiting significant sequence homology with food allergens were retrieved in chlorella extracts, viz. calmodulin (A0A2P6TFR8), which is related to troponin c (D7F1Q2), and fructose-bisphosphate aldolase (A0A2P6TDD0). Specific serum screenings based on immunochemical tests should be undertaken to confirm or rule out the allergenicity of the identified proteins.

Newly defined allergens in the WHO/IUIS Allergen Nomenclature Database during 01/2019-03/2021.

The WHO/IUIS Allergen Nomenclature Database (http://allergen.org) provides up‐to‐date expert‐reviewed data on newly discovered allergens and their unambiguous nomenclature to allergen researchers worldwide. This review discusses the 106 allergens that were accepted by the Allergen Nomenclature Sub‐Committee between 01/2019 and 03/2021. Information about protein family membership, patient cohorts, and assays used for allergen characterization is summarized. A first allergenic fungal triosephosphate isomerase, Asp t 36, was discovered in Aspergillus terreus. Plant allergens contained 1 contact, 38 respiratory, and 16 food allergens. Can s 4 from Indian hemp was identified as the first allergenic oxygen‐evolving enhancer protein 2 and Cic a 1 from chickpeas as the first allergenic group 4 late embryogenesis abundant protein. Among the animal allergens were 19 respiratory, 28 food, and 3 venom allergens. Important discoveries include Rap v 2, an allergenic paramyosin in molluscs, and Sal s 4 and Pan h 4, allergenic fish tropomyosins. Paramyosins and tropomyosins were previously known mainly as arthropod allergens. Collagens from barramundi, Lat c 6, and salmon, Sal s 6, were the first members from the collagen superfamily added to the database. In summary, the addition of 106 new allergens to the previously listed 930 allergens reflects the continuous linear growth of the allergen database. In addition, 17 newly described allergen sources were included.

Mapping B-Cell Epitopes for Nonspecific Lipid Transfer Proteins of Legumes Consumed in India and Identification of Critical Residues Responsible for IgE Binding.

Nonspecific lipid transfer proteins (nsLTPs) have been categorized as panallergens and display widespread occurrence across plant-kingdom. Present study, investigated B-cell epitopes for LTPs from chickpea, mung-bean, cowpea, pigeon-pea, and soybean via in silico methods. In-silico predicted regions were evaluated for epitope-conservancy and property-based peptide similarity search by different allergen databases. Additionally, the in-silico predicted regions were compared with the experimentally validated epitopes of peach-LTP. Sequence-homology studies showed that chickpea and mung-bean LTPs shared significant homology, i.e., >70% and >60%, respectively, with other LTP allergens from lentil, garden-pea, peanut, etc. Phylogenetic-analysis also showed chickpea and mung-bean LTPs to be closely related to allergenic LTPs from lentil and peanut, respectively. Epitope-conservation analysis showed that two of the predicted B-cell epitopic regions in chickpea and mung-bean LTPs were also conserved in other allergenic LTPs from peach, peanut, garden-pea, lentil, and green-bean, and might serve as conserved B-cell epitopes of the LTP protein family. Property-distance index values for chickpea and mung-bean LTPs also showed that most of the epitopes shared similarity with the reported allergens like-lentil, peanut, apple, plum, tomato, etc. Present findings, may be explored for identification of probable allergenicity of novel LTPs, on the basis of the reported conserved B-cell epitopes, responsible for potential cross-reactivity.

Novel Allergen Discovery through Comprehensive De Novo Transcriptomic Analyses of Five Shrimp Species.

Shellfish allergy affects 2% of the world’s population and persists for life in most patients. The diagnosis of shellfish allergy, in particular shrimp, is challenging due to the similarity of allergenic proteins from other invertebrates. Despite the clinical importance of immunological cross-reactivity among shellfish species and between allergenic invertebrates such as dust mites, the underlying molecular basis is not well understood. Here we mine the complete transcriptome of five frequently consumed shrimp species to identify and compare allergens with all known allergen sources. The transcriptomes were assembled de novo, using Trinity, from raw RNA-Seq data of the whiteleg shrimp (Litopenaeus vannamei), black tiger shrimp (Penaeus monodon), banana shrimp (Fenneropenaeus merguiensis), king shrimp (Melicertus latisulcatus), and endeavour shrimp (Metapenaeus endeavouri). BLAST searching using the two major allergen databases, WHO/IUIS Allergen Nomenclature and AllergenOnline, successfully identified all seven known crustacean allergens. The analyses revealed up to 39 unreported allergens in the different shrimp species, including heat shock protein (HSP), alpha-tubulin, chymotrypsin, cyclophilin, beta-enolase, aldolase A, and glyceraldehyde-3-phosphate dehydrogenase (G3PD). Multiple sequence alignment (Clustal Omega) demonstrated high homology with allergens from other invertebrates including mites and cockroaches. This first transcriptomic analyses of allergens in a major food source provides a valuable resource for investigating shellfish allergens, comparing invertebrate allergens and future development of improved diagnostics for food allergy.

Protein Engineering of Mung Bean (Vigna radiata (L.) Wilczek) 8Sα Globulin with Lactostatin

Mung bean is a well-known good source of protein. To increase its bioactivity, economic value, and nutritional content as a functional food and food additive, lactostatin (IIAEK), a cholesterol-lowering bioactive peptide, was engineered into mung bean 8Sα globulin, a major storage protein. The results showed that the mutated 8Sα globulin has a significant bile acid binding capacity (cholesterol-lowering activity) up to 47.25%. Moreover, superimposed mutant (Mut2) and wild-type (Wt) 3D protein structures showed a 93–97% identity, indicating that the mutant proteins are stable. Ultra-performance liquid chromatography(UPLC)-based assay showed similar retention time for wild-type and mutant protein samples. Both IIAEK peptide standard and Mut2 digest had comparable baseline peaks corresponding to the same molecular size based on the liquid chromatography-mass spectrometry (LC-MS) data. A 573.36-Da mass spectrum was seen in Mut2, which indicates that Mut2 8Sα globulin has been successfully mutated and digested to release the bioactive peptide, IIAEK. In vitro bile acid binding capacity showed that the 6-h Wt and 12-h engineered protein (Mut2) digests had the highest activity. Lastly, potential allergenicity was checked in the Allergen Database for Food Safety (ADFS) and the AllerBase database, and the IIAEK peptide matched the Bos d 5 epitopes. This study provides a strong foundation and basis for mung bean nutrition improvement, development of cholesterol-lowering food supplements, and protein engineering of other food proteins.

Evaluating potential risks of food allergy of novel food sources based on comparison of proteins predicted from genomes and compared to www.AllergenOnline.org

Potential proteins from three novel food sources (Chlorella variabilis, Galdieria sulphuraria, and Fusarium strain flavolapis) were predicted from genomic sequences and were evaluated for potential risks of allergic cross-reactivity by comparing the predicted amino acid sequences against the allergens in the www.AllergenOnline.org (AOL) database. The preliminary analysis used CODEX Alimentarius limits of >35% identity over 80 amino acids to evaluate the predicted proteins which include many evolutionarily conserved proteins. Regulators might expect clinical serum IgE tests based on identity matches above the criteria if the proteins were introduced in genetically engineered crops. Some regulators have the same expectations for proteins in novel foods. To address the inequality of extensively conserved sequences, we compared the predicted proteins from curated genomes of 23 highly diverse allergenic species from animals, plants and arthropods as well as humans to AOL sequences and compiled identities. Identity matches greater than CODEX limits (>35% ID over 80 AA) are common for many proteins that are conserved through extensive evolution but are not predictive of published allergy risks based on observed taxonomic cross-reactivity. Therefore, we recommend changes in the allergen databases or methods of identifying matches for risk evaluation of new food sources. Our results provide critical data for redefining allergens in AOL or for providing guidance on more predictive sequence identity matches for risk assessment of possible risks of food allergy.

Molecular and immunological characterization of grass carp (Ctenopharyngodon idella) parvalbumin Cten i 1: A major fish allergen in Hong Kong.

Grass carp is the most commonly consumed fish species in Hong Kong. The allergenicity of grass carp and its allergen content are yet to be reported. This study characterized the major allergen in grass carp and investigated its allergenicity. Sixty-nine subjects with history of IgE-mediated allergic reaction to grass carp were recruited. The protein content in steamed grass carp extract was resolved by SDS-PAGE, and the major allergen was identified by immunoblotting with serum from subjects allergic to grass carp. The identity of allergen was elucidated by mass spectrometry and amino acid sequence obtained by amplifying the specific gene from cDNA library of grass carp. The cross-reactivity between parvalbumins from grass carp and other phylogenetically close (common carp) or commercially important (cod and salmon) species was investigated by competitive inhibition ELISA. A major IgE-binding protein was found at approximately 9kDa and identified as parvalbumin by immunoblotting and mass spectrometry. Grass carp parvalbumin was more allergenic than common carp, salmon, and cod parvalbumins despite sharing high sequence homology. This newly identified major allergenic parvalbumin isoform from grass carp was registered as Cten i 1 in the World Health Organization and International Union of Immunological Societies allergen database. Grass carp parvalbumin is identified as the major fish allergen in Hong Kong. The strong allergenicity of Cten i 1 contributes to the high IgE reactivity of grass carp. Grass carp, among other fish species, should be considered when managing fish-allergic patients.

Transcriptome-based analysis of putative allergens of Chorioptes texanus

BackgroundMites of the genus Chorioptes are non-burrowing and cause mange in a wide range of domestic and wild animals including cattle, horses, sheep, goats, panda, moose, camelids, mydaus and alpacas. Molecular biology and host-parasite interactions of Chorioptes texanus are poorly understood, and only a few C. texanus genes and transcript sequences are available in public databases including the allergen genes.MethodsChorioptes texanus RNA was isolated from mites, and the transcriptome of C. texanus was analyzed using bioinformatics tools. Chorioptes texanus unigenes were compared with the allergen protein sequences from the mite allergen database website to predict the potential allergens. Chorioptes texanus putative allergen unigenes were compared with hydrolase genes by building a C. texanus hydrolase gene library with the best match of the homologous sequences. Three allergen genes were cloned and expressed, their recombinant proteins were purified and their allergenic activities were preliminarily investigated.ResultsTranscriptome sequencing (RNA-Seq) of C. texanus was analyzed and results demonstrated that 33,138 unigenes were assembled with an average length of 751 bp. A total of 15,130 unigenes were annotated and 5598 unigenes were enriched in 262 KEGG signaling pathways. We obtained 209 putative allergen genes and 34 putative allergen-hydrolase genes. Three recombinant allergen proteins were observed to induce different degrees of allergic reactions on rabbit skin.ConclusionsThe present transcriptome data provide a useful basis for understanding the host-parasite interaction and molecular biology of the C. texanus mite. The allergenic activities of recombinant Euroglyphus maynei 1-like (Eur m 1-like) protein, Dermatophagoides ptreronyssinus 1-like (Der p 1-like) protein and Dermatophagoides ptreronyssinus 7-like (Der p 7-like) protein were preliminarily investigated by intradermal skin test. Meanwhile, differences in eosinophil counts were observed in different injected sites of the skin. The identification of putative allergen genes and hydrolase genes offers opportunities for the development of new diagnostic, prevention and treatment methods.

Chitinases as Food Allergens.

Food allergies originate from adverse immune reactions to some food components. Ingestion of food allergens can cause effects of varying severity, from mild itching to severe anaphylaxis reactions. Currently there are no clues to predict the allergenic potency of a molecule, nor are cures for food allergies available. Cutting-edge research on allergens is aimed at increasing information on their diffusion and understanding structure-allergenicity relationships. In this context, purified recombinant allergens are valuable tools for advances in the diagnostic and immunotherapeutic fields. Chitinases are a group of allergens often found in plant fruits, but also identified in edible insects. They are classified into different families and classes for which structural analyses and identification of epitopes have been only partially carried out. Moreover, also their presence in common allergen databases is not complete. In this review we provide a summary of the identified food allergenic chitinases, their main structural characteristics, and a clear division in the different classes.