Efficient soluble production of folded cat allergen Fel d 1 in Escherichia coli.

The major cat allergen Fel d 1 is one of the most common and potent causes of animal related allergy. Medical treatment of cat allergy has relied on immunotherapy carried out with cat dander extract. This approach has been problematic, mainly due to inconsistent levels of the major allergen in the produced extracts. Recombinant DNA technology has been proposed as an alternative method to produce more consistent pharmaceuticals for immunotherapy and diagnostics of allergy. Current approaches to produce recombinant Fel d 1 (recFel d 1) in the cytoplasm of Escherichia coli have however resulted in protein folding deficiencies and insoluble inclusion body formation, requiring elaborate in vitro processing to acquire folded material. In this study, we introduce an efficient method for cytoplasmic production of recFel d 1 that utilizes eukaryotic folding factors to aid recFel d 1 to fold and be produced in the soluble fraction of E. coli. The solubly expressed recFel d 1 is shown by biophysical in vitro experiments to contain structural disulfides, is extremely stable, and has a sensitivity for methionine sulfoxidation. The latter is discussed in the context of functional relevance.

Design, production and immunomodulatory potency of a novel allergen bioparticle.

Allergen immunotherapy (AIT) is the only disease-modifying treatment with evidence for sustained efficacy. However, it is poorly developed compared to symptomatic drugs. The main reasons come from treatment duration implying monthly injections during 3 to 5 years or daily sublingual use, and the risk of allergic side-effects. To become a more attractive alternative to lifelong symptomatic drug use, improvements to AIT are needed. Among the most promising new immunotherapy strategies is the use of bioparticles for the presentation of target antigen to the immune system as they can elicit strong T cell and B cell immune responses. Virus-like particles (VLPs) are a specific class of bioparticles in which the structural and immunogenic constituents are from viral origin. However, VLPs are ill-suited for use in AIT as their antigenicity is linked to structure. Recently, synthetic biology has been used to produce artificial modular bioparticles, in which supramolecular assemblies are made of elements from heterogeneous biological sources promoting the design and use of in vivo-assembling enveloped bioparticles for viral and non-viral antigens presentation. We have used a coiled-coil hybrid assembly for the design of an enveloped bioparticle (eBP) that present trimers of the Der p 2 allergen at its surface, This bioparticle was produced as recombinant and in vivo assembled eBPs in plant. This allergen biotherapeutic was used to demonstrate i) the capacity of plants to produce synthetic supramolecular allergen bioparticles, and ii) the immunomodulatory potential of naturally-assembled allergen bioparticles. Our results show that allergens exposed on eBPs induced a very strong IgG response consisting predominantly of IgG2a in favor of the TH1 response. Finally, our results demonstrate that rDer p 2 present on the surface of BPs show a very limited potential to stimulate the basophil degranulation of patient allergic to this allergen which is predictive of a high safety potential.

Identification and in silico bioinformatics analysis of PR10 proteins in cashew nut.

Proteins from cashew nut can elicit mild to severe allergic reactions. Three allergenic proteins have already been identified, and it is expected that additional allergens are present in cashew nut. pathogenesis-related protein 10 (PR10) allergens from pollen have been found to elicit similar allergic reactions as those from nuts and seeds. Therefore, we investigated the presence of PR10 genes in cashew nut. Using RNA-seq analysis, we were able to identify several PR10-like transcripts in cashew nut and clone six putative PR10 genes. In addition, PR10 protein expression in raw cashew nuts was confirmed by immunoblotting and liquid chromatography-mass spectrometry (LC-MS/MS) analyses. An in silico allergenicity assessment suggested that all identified cashew PR10 proteins are potentially allergenic and may represent three different isoallergens.

Barley produced Culicoides allergens are suitable for monitoring the immune response of horses immunized with E. coli expressed allergens.

Insect bite hypersensitivity is an allergic dermatitis of horses caused by bites of Culicoides midges. Sufficient amount of pure, endotoxin-free allergens is a prerequisite for development and monitoring of preventive and therapeutic allergen immunotherapy. Aims of the study were to compare the Culicoides nubeculosus (Cul n) allergens Cul n 3 and Cul n 4, produced in transgenic barley grains with the corresponding E. coli or insect cells expressed proteins for measuring antibody and cytokine responses. Allergen-specific IgG responses were measured by ELISA in sera from twelve horses not exposed to Culicoides, before and after vaccination with E. coli-rCul n 3 and 4. Before vaccination no IgG binding to the barley and insect cell produced proteins was detected and a similar increase in specific IgG was observed after vaccination. While IgG levels to the E.coli expressed proteins were higher in the post-vaccination sera, some background binding was observed pre-vaccination. In vitro re-stimulation of PBMC was performed for measurements of cytokines. E. coli expressed proteins resulted in high background in PBMC from non-vaccinated controls. The barley and insect cell expressed proteins induced similar amount of IFN-γ and IL-4 in PBMC from vaccinated horses. Barley produced allergens are promising tools for use in immunoassays.

Immunological Comparison of Native and Recombinant Hen's Egg Yolk Allergen, Chicken Serum Albumin (Gal d 5), Produced in Kluveromyces lactis.

Chicken serum albumin (CSA) is a hen's egg yolk allergen causing IgE-mediated allergy. The objective of this study was to produce a recombinant version of CSA and compare its IgE reactivity to natural CSA (nCSA). CSA was cloned and expressed as a soluble fraction in the yeast Kluyveromyces lactis (K. lactis) protein expression system. The gene encoding CSA was amplified with a C-terminal hemagglutinin epitope tag by polymerase chain reaction (PCR) and cloned into the pKLAC2 expression vector prior to transforming into K. lactis. Recombinant CSA (rCSA) was purified by immunoprecipitation. Twenty-one patients allergic to hen's egg white were examined for sensitisation against nCSA. 38% of patients were found to be sensitised to CSA based on Western immunoassay. Immunoglobulin E (IgE) binding capacity of rCSA and nCSA was analysed by ELISA using sera from patients sensitised to CSA. Levels of IgE-binding were similar for both the recombinant and the natural CSA, indicating the existence of similar epitopes. rCSA produced in this study is a potential candidate to be used in component-resolved diagnosis (CRD) of egg yolk allergy. The usefulness of rCSA in CRD of egg yolk allergy warrants further characterisation using sera from patients with allergy to hen's egg yolk in future studies.

lncRNA profiling in NCI-H292 cells after stimulation with Dermatophagoides farinae extracts.

Airway epithelium cells are the first line of defense against airborne allergens. When cultured, epithelial cells can be exposed to various allergens, providing an ideal model to investigate allergic disorders. This study sought to characterize the profile of long noncoding (lnc) RNAs, which can regulate gene expression and exert functions in diverse cellular processes, in airway epithelial cells exposed to house dust mite allergens. NCI-H292 cells were exposed to house dust mite extract for 24 h. RNA expression was profiled in exposed and unexposed cells. There were 270 lncRNAs that were differentially expressed (fold change ≥ 2, P < 0.05) in NCI-H292 cells after stimulation with Dermatophagoides farinae (house dust mite) extracts. Furthermore, 119 lncRNAs and 22 messenger RNAs were co-expressed. Gene Ontology analysis showed that these under-regulated and up-regulated lncRNAs were associated with biological process, cellular component, and molecular function. After bioinformatic analysis of significantly regulated signaling pathways, we found these lncRNAs may target 16 gene pathways, including glycolysis, axon guidance, ErbB signaling, and mitogen-activated protein kinases (MAPK) signaling. The identification of differentially regulated lncRNAs in NCI-H292 cells after stimulation with Dermatophagoides farinae extracts, as well as their target gene pathways, can provide insight to the etiology and pathogenesis of allergy.

Cloning, expression, and purification of recombinant major mango allergen Man i 1 in Escherichia coli.

In recent years, the number of people around the world who suffer from fruit allergies has increased. Mango can induce anaphylaxis, and two major mango allergens have been identified - Man i 1 and Man i 2. Apart from their molecular weights and pI values, no other information about them is known. This work identifies the DNA and amino acid sequences of Man i 1 and constructs an expression system for recombinant Man i 1 (rMan i 1). Firstly, 3' and 5' RACE assays were used to identify the cDNA fragment of Man i 1. Subsequently, the full length of Man i 1 cDNA was inserted into a pET-21a(+) vector, and the inserted plasmid was transformed to Escherichia coli BL21 (DE3) to express rMan i 1. The conditions for the expression of rMan i 1, including IPTG concentration, induction temperature, and induction time, were optimized. The highest amount of soluble rMan i 1 was obtained after induction with 0.1 mM IPTG at 16 °C for 20 h. The His-tagged rMan i 1 was purified using Ni-NTA agarose and its identity was verified using an anti-histidine antibody and the serum of a mango-allergic person. Additionally, rMan i 1 was identified as glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and shared 86.2% identity in amino acid sequence of GAPDH from wheat. Finally, an E. coli expression system of rMan i 1 was established, with the potential to be used in immunotherapy against mango allergy or the development of assays for detecting the residues of mango allergens.

Identification and Assessment of the Potential Allergenicity of 7S Vicilins in Olive (Olea europaea L.) Seeds.

Olive seeds, which are a raw material of interest, have been reported to contain 11S seed storage proteins (SSPs). However, the presence of SSPs such as 7S vicilins has not been studied. In this study, following a search in the olive seed transcriptome, 58 sequences corresponding to 7S vicilins were retrieved. A partial sequence was amplified by PCR from olive seed cDNA and subjected to phylogenetic analysis with other sequences. Structural analysis showed that olive 7S vicilin contains 9 α-helixes and 22 ß-sheets. Additionally, 3D structural analysis displayed good superimposition with vicilin models generated from Pistacia and Sesamum. In order to assess potential allergenicity, T and B epitopes present in these proteins were identified by bioinformatic approaches. Different motifs were observed among the species, as well as some species-specific motifs. Finally, expression analysis of vicilins was carried out in protein extracts obtained from seeds of different species, including the olive. Noticeable bands were observed for all species in the 15-75 kDa MW interval, which were compatible with vicilins. The reactivity of the extracts to sera from patients allergic to nuts was also analysed. The findings with regard to the potential use of olive seed as food are discussed.

Expression of a codon-optimised recombinant Ara h 2.02 peanut allergen in Escherichia coli.

Current diagnostic tools for peanut allergy using crude peanut extract showed low predictive value and reduced specificity for detection of peanut allergen-specific immunoglobulin E (IgE). The Ara h 2.02, an isoform of the major peanut allergen Ara h 2, contains three IgE epitope recognition sequence of 'DPYSPS' and may be a better reagent for component resolve diagnosis. This research aimed to generate a codon-optimised Ara h 2.02 gene for heterologous expression in Escherichia coli and allergenicity study of this recombinant protein. The codon-optimised gene was generated by PCR using overlapping primers and cloned into the pET-28a (+) expression vector. Moderate expression of a 22.5 kDa 6xhistidine-tagged recombinant Ara h 2.02 protein (6xHis-rAra h 2.02) in BL21 (DE3) host cells was observed upon induction with 1 mM isopropyl ß-D-1-thiogalactopyranoside (IPTG). The insoluble recombinant protein was purified under denaturing condition using nickel-nitrilotriacetic acid (Ni-NTA) affinity chromatography and refolded by dialysis in decreasing urea concentration, amounting to a yield of 74 mg/l of expression culture. Matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) and immunoblot analysis confirmed the production of the recombinant 6xHis-rAra h 2.02. The refolded recombinant 6xHis-rAra h 2.02, with or without adjuvant, was able to elicit comparable level of allergen-specific IgE and IgG1 in sensitised Balb/c mice. In addition, the specific IgE antibodies raised against the recombinant protein were able to recognise the native Ara h 2 protein, demonstrating its allergenicity and potential as a reagent for diagnosis and therapeutic study.

Transcriptome analysis of Solanum melongena L. (eggplant) fruit to identify putative allergens and their epitopes.

Eggplant is the third most important Solanaceae crop after tomato and potato, particularly in India and China. A transcriptome analysis of eggplant's fruit was performed to study genes involved in medicinal importance and allergies. Illumina HiSeq 2000 system generated 89,763,638 raw reads (~18 Gb) from eggplant. High quality reads (59,039,694) obtained after trimming process, were assembled into a total of 149,224 non redundant set of transcripts. Out of 80,482 annotated sequences of eggplant fruit (BLASTx results against nr-green plant database), 40,752 transcripts showed significant similarity with predicted proteins of Solanum tuberosum (51%) followed by Solanum lycopersicum (34%) and other sequenced plant genomes. With BLASTx top hit analysis against existing allergens, a total of 1986 homologous allergen sequences were found, which had >37% similarity with 48 different allergens existing in the database. From the 48 putative allergens, 526 B-cell linear epitopes were identified using BepiPred linear epitope prediction tool. Transcript sequences generated from this study can be used to map epitopes of monoclonal antibodies and polyclonal sera from patients. With the support of this whole transcriptome catalogue of eggplant fruit, complete list of genes can be predicted based on which secondary structures of proteins may be modeled.

The Innovation from Innsbruck: Plant-based Allergen Recombinantly Produced in Green Alga.

An innovation in biotechnology: for the first time, researchers from MCI Innsbruck and the University of Salzburg have manufactured and purified a plant-based allergen in a green alga and opened the door to a specific immunotherapy against allergies. Their vision: to replace the unpleasant injection with oral administration, as its production is both simple and cost-effective.

Molecular Cloning and Expression of a New Allergen of Acacia farnesiana (Aca f 2).

Inhalation of pollens from different species of Acacia is a common cause of respiratory allergy in tropical areas of the world. Acacia farnesiana is commonly used as street trees in towns and ornamental shade trees in parks and gardens throughout arid and semi-arid regions of Asia. This study aimed to produce and purify the A. farnesiana pollen profilin (Aca f 2) and evaluate its nucleotide sequence homology with profilins of common allergenic plants to predict allergenic cross-reactivity. Thirty-nine patients who were allergic to Acacia pollens were included in the study. Cloning of Acacia profilin-coding sequence was performed by polymerase chain reaction using primers from Acacia pollen RNA. The cDNA of Acacia pollen profilin was then expressed in Escherichia coli using pET-21b(+) vector and purified by metal affinity chromatography. Immunoreactivity of the recombinant Acacia profilin (rAca f 2) was evaluated by specific ELISA, immunoblotting, and inhibition assays. The coding sequence of the Acacia profilin cDNA was recognized as a 399-bp open reading frame encoding 133 amino acid residues. Eighteen patients (18/39, 46.15%) had significant specific IgE levels against Aca f 2. Immunodetection and inhibition assays indicated that purified Aca f 2 might be the same as that in the crude extract. Aca f2, the first allergen from A. farnesiana pollen, was identified as belonging to the family of profilins. The amino acid sequence homology analysis showed high cross-reactivity between Aca f 2 and other profilins from botanically unrelated common allergenic plants.

CONSTRUCTION AND EXPRESSION OF DERMATOPHAGOIDES PTERONYSSINUS GROUP 1 MAJOR ALLERGEN T CELL FUSION EPITOPE PEPTIDE VACCINE VECTOR BASED ON THE MHC II PATHWAY.

UNLABELLED: Backgound and aims: Dermatophagoides peteronyssinus is one of the important house dust mites responsible for allergic asthma that can be tentatively managed by specific immunotherapy. The present study was to construct a vector encoding T-cell epitopes of major allergen group 1 of Dermatophagoides pteronyssinus as a vaccine delivered by MHC class II pathway. METHODS: the nucleotide sequences of the 3 target genes were synthesized, including TAT, IhC and the recombinant fragment of Der p 1 encoding 3 T-cell epitopes. After amplification of the 3 target fragments by PCR and digestion with corresponding restriction endonucleases, the recombinant gene TAT-IhC-Der p 1-3T was ligated using T4 DNA ligase and inserted into the prokaryotic expression vector pET28a(+) to construct the recombinant plasmid pET- 28a(+)-TAT-IhC-Der p 1-3T, which was confirmed by digestion with restriction endonucleases and sequencing. The recombinant vector was transformed into E. coli strain BL21 (DE3) and induced with IPTG, and the induced protein TAT-IhC-Der p1-3T was detected by SDS-PAGE. After purification, the recombinant protein was confirmed by Western blotting and its allergenicity tested using IgE-binding assay. RESULTS: the recombinant plasmid pET-28a-TAT-IhCDer p1-3T was successfully constructed as confirmed by restriction endonuclease digestion and sequencing, and the expression of the recombinant protein TAT-IhC-Der p1-3T was induced in E. coli. Western blotting verified successfull purification of the target protein, which showed a stronger IgE-binding ability than Der p1. CONCLUSION: we successfully constructed the recombinant expression vector pET-28a-TAT-IhC-Der p1-3T expressing a T-cell epitope vaccine delivered by MHC II pathway with strong IgE-binding ability, which provides a basis for further study on specific immunotherapy via MHC class II pathway.

Antecedentes y objetivo: el Dermatophagoides peteronyssinus es uno de los principales ácaros del polvo doméstico responsables del asma alérgica que se pueden administrar provisionalmente para una inmunoterapia específica. El presente estudio busca construir un vector que codifique epítopos de células T del grupo de alérgenos principal, el Grupo 1 de Dermatophagoides pteronyssinus como una vacuna suministrada mediante la vía MHC de clase II. Métodos: se sintetizaron las secuencias de nucleótidos de los 3 genes objetivo, incluyendo TAT, IhC y el fragmento recombinante de Der p 1 encargado de codificar 3 epítopos de célula T. Después de la amplificación de los 3 fragmentos objetivo por PCR y digestión con endonucleasas de restricción correspondientes, el gen recombinante TAT-IhC-Der p 1-3T se ligó usando T4 DNA ligasa y se insertó en el vector de expresión procariota pET28a (+) para construir el plásmido recombinante pET 28a (+)-TAT-IHC-Der p 1-3T, que se confirmó por digestión con endonucleasas de restricción y secuenciación. El vector recombinante se transformó en E. coli cepa BL21 (DE3) y se indujo con IPTG, y la proteína inducida TATIHC- Der p1-3T se detectó mediante SDS-PAGE. Después de la purificación, la proteina recombinante se confirmó por análisis de inmunotransferencia (Western blot) y se probó su alergenicidad usando el ensayo de unión a IgE. Resultados: el plásmido recombinante pET-28a-TATIHCDer p1-3T se construyó con éxito, se confirmó por digestión con endonucleasas de restricción y la secuenciación y la expresión de la proteína recombinante TAT-IHCDer p1-3T fue inducida en E. coli. Purificación con éxito verificada mediante Western blot de la proteína objetivo, que mostró una capacidad de unión a IgE más fuerte que Der p1. Conclusión: hemos construido con éxito el vector de expresión recombinante pET-28a-TAT-IHC-Der p1-3T que expresa una vacuna de epítopo de células T administrada por vía MHC II con fuerte capacidad de union a IgE. Este trabajo proporciona una base para seguir estudiando la inmunoterapia específica mediante la vía MHC de clase II.

Expression, purification and identification of Pla a1 in a codon-optimized Platanus pollen allergen.

The present study aimed to express, purify and identify the major allergen gene, Pla a1, in Platanus pollen. According to previous studies, the major gene sequences of the Pla a1 allergen were obtained and codon optimization and synthesis of the genome were performed using DNAStar software. Following binding of the target gene fragment and the pET-44a vector, the JM109 cells were transfected to produce positive clones. The vectors were then transformed into Escherichia coli Rosetta cells to induce the expression of the target protein. The exogenous protein was purified using affinity chromatography and was identified by western blot analysis. Pla a1, the major allergen protein in Platanus pollen, was successfully isolated and this exogenous protein was purified using affinity chromatography. The present study was the first, to the best of our knowledge, to obtain expression of the allergen recombinant protein, Pla a1, fused with a Strep-TagII via codon optimization and provided the basis for the preparation of allergens with high purity, recombinant hypoallergenic allergens and allergen nucleic acid vaccines.

Auto-induction for high yield expression of recombinant novel isoallergen tropomyosin from King prawn (Melicertus latisulcatus) for improved diagnostics and immunotherapeutics.

Food allergies are increasing worldwide, demonstrating a considerable public health concern. Shellfish allergy is one of the major food groups causing allergic sensitization among adults and children, affecting up to 2% of the general world population. Tropomyosin (TM) is the major allergen in shellfish and frequently used in the diagnosis of allergic sensitization and the detection of cross-contaminated food. To improve and establish better and more sensitive diagnostics for allergies and immunotherapeutics, large quantities of pure allergens are required. To establish a reproducible method for the generation of pure recombinant tropomyosin we utilized in this study different Escherichia coli strains (NM522, TOP10 and BL21(DE3)RIPL). In addition, isopropyl-ß-D-thiogalactoside (IPTG) induction was compared with a novel auto-induction system to allow the generation of larger quantities of recombinant allergen. We demonstrated that the B-strain of E. coli is better for the expression of TM compared to the K-strain. Moreover, a higher yield could be achieved when using the auto-induction system, with up to 62 mg/l. High yield expressed recombinant TM from King prawn (KP) was compared to recombinant TM from Black tiger prawn (Pen m 1). We demonstrated that recombinant TM from KP and known isoallergen Pen m 1 have very similar molecular and immunological characteristics. Overall, we demonstrate that auto-induction can be used to express larger quantities of recombinant allergens for the development of diagnostic, to quantify allergens as well as immunotherapeutics employing isoallergens.

A DNA vaccine encoding a chimeric allergen derived from major group 1 allergens of dust mite can be used for specific immunotherapy.

Immunization with DNA-based constructs has been shown to be against the antigen and the response is skewed in such a way as to ameliorate the symptoms of allergic disease. This approach is particularly useful in the treatment of allergic inflammatory diseases, such as asthma. The major group 1 allergen from house dust mites is one of the triggers of allergic asthma. This study explores whether a chimeric gene R8, derived from the major group 1 allergen of house dust mite species (Dermatophagoides farinae and Dermatophagoides pteronyssinus), can be expressed in Human Embryonic Kidney 293 cells (HEK 293 T) and whether such a construct can be used as a DNA vaccine in asthma therapy. The eukaryotic expression vector pcDNA3.1 was used to express the R8 molecule in HEK 293 T cells and successful expression of R8 was confirmed using a fluorescence microscope and western blot analysis. The efficacy of R8 as DNA vaccine was also assessed in a mouse asthma model. The in vivo data showed that R8 rectified the TH1/TH2 imbalance typical of allergic inflammation and stimulated the proliferation of regulatory T (Treg) cells. Immunization with the R8 construct also decreased serum allergen-specific IgE production in this mouse asthma model. Our findings suggest that R8 may be a feasible potential DNA vaccine for specific immunotherapy (SIT) in the treatment of allergic asthma.

Characterization of the house dust mite allergen Der p 21 produced in Pichia pastoris.

BACKGROUND: The development of recombinant house dust mite (HDM) allergens opened the way for the in-depth characterization of these molecules but also provided new opportunities to refine the diagnostic procedures of HDM allergy as well as the allergen-specific immunotherapy through tailor-made treatments. OBJECTIVE: In the present study, the HDM allergen Der p 21 was expressed in Pichia pastoris under a secreted form. The physico-chemical as well as the allergenic characterizations of recombinant Der p 21 (rDer p 21) were performed. METHODS: Purified rDer p 21, secreted from recombinant P. pastoris was characterized by CD and MS analysis and the frequency of IgE reactivity was determined by ELISA using 96 sera of HDM-allergic patients from Bangkok. The direct airway epithelial cell activation by rDer p 21 was also evaluated. RESULTS: rDer p 21 was highly expressed under a secreted form in P. pastoris. The physico-chemical characterization of purified rDer p 21 showed that the allergen displayed appropriate α-helix secondary structure content although a two amino acids truncation at the N-terminus of the protein was evidenced by MS. The prevalence of IgE reactivity to rDer p 21 reached 25% in the cohort of the HDM-allergic patients. rDer p 21 could trigger IL-8 production in airway epithelial cells through TLR2-dependent signaling. CONCLUSION: Properly folded rDer p 21 produced in P. pastoris is appropriate for HDM allergy diagnosis as well for future recombinant allergen-based specific immunotherapy.

Production and analysis of recombinant tree nut allergens.

Allergic reactions to tree nuts are a growing global concern as the number of affected individuals continues to rise. Unlike some food allergies, tree nuts can cause severe reactions that persist throughout life. The tree nuts discussed in this review include those most commonly responsible for allergic reactions: cashew, almond, hazelnut, walnut, pecan, Brazil nut, pistachio, and chestnut. The native allergenic proteins derived from tree nuts are frequently difficult to isolate and purify and may not be adequately represented in aqueous nut protein extracts. Consequently, defined recombinant allergens have become useful reagents in a variety of immunoassays aimed at the diagnosis of tree nut allergy, assessing cross-reactivity between various nuts and other seeds, mapping of IgE binding epitopes, and analyzing the effects of the food matrix, food processing, and gastric digestion on allergenicity. This review describes the approaches that can be used for the production of recombinant tree nut allergens and addresses key issues associated with their production and downstream applications.