Epitope mapping and the effects of various factors on the immunoreactivity of main allergens in egg white.

Egg white has high protein content and numerous biological/functional properties. However, reported allergenicity for some of the proteins in egg white is an issue that needs to be paid exclusive attention. A consideration of the structure of IgE epitopes and their sequences, as well as a comprehensive understanding of the effects of various processes on epitopes and the impact of the gastrointestinal tract on them, can help target such issues. The current study focuses on the identified IgE epitopes in egg white proteins and evaluation of the effects of the gastrointestinal digestion, carbohydrate moiety, food matrix, microbial fermentation, recombinant allergen, heat treatment, Maillard reaction and combination of various processes and gastrointestinal digestion on egg white allergenicity. Although the gastrointestinal tract reduces the immunoreactivity of native egg white proteins, some of the IgE epitope-containing fragments remain intact during the digestion process. It has been found that the gastrointestinal tract can have both positive and negative impacts on the IgE binding activities of egg white proteins. Elimination of the carbohydrate moiety leads to a reduction in the immunoreactivity of ovalbumin. But, such effects from the carbohydrate parts in the IgE binding activity need to be explored further. In addition, the interaction between the egg white proteins and the food matrix leads to various effects from the gastrointestinal tract on the digestion of egg white proteins and their subsequent immunoreactivity. Further on this matter, studies have shown that both microbial fermentation and Maillard reaction can reduce the IgE binding activities of egg white proteins. Also, as an alternate approach, the thermal process can be used to treat the egg white proteins, which may result in the reduction or increase in their IgE binding activities depending on the conditions used in the process. Overall, based on the reported data, the allergenicity levels of egg white proteins can be mitigated or escalated depending on the conditions applied in the processing of the food products containing egg white. So far, no practical solutions have been reported to eliminate such allergenicity.

Threshold of Reactivity and Tolerance to Precautionary Allergen-Labelled Biscuits of Baked Milk- and Egg-Allergic Children.

Extremely sensitive food-allergic patients may react to very small amounts of allergenic foods. Precautionary allergen labelling (PAL) warns from possible allergenic contaminations. We evaluated by oral food challenge the reactivity to a brand of PAL-labelled milk- and egg-free biscuits of children with severe milk and egg allergy. We explored the ability of proteomic methods to identify minute amounts of milk/egg allergens in such biscuits. Traces of milk and/or egg allergens in biscuits were measured by two different liquid-chromatography-mass spectrometry methods. The binding of patient's serum with egg/milk proteins was assessed using immunoblotting. None of the patients reacted to biscuits. Egg and milk proteins were undetectable with a limit of detection of 0.6 µg/g for milk and egg (method A), and of 0.1 and 0.3 µg /g for milk and egg, respectively (method B). The immunoblots did not show milk/egg proteins in the studied biscuits. Milk/egg content of the biscuits is far lower than 4 µg of milk or egg protein per gram of product, the minimal doses considered theoretically capable of causing reactions. With high sensitivity, proteomic assessments predict the harmlessness of very small amount of allergens in foods, and can be used to help avoiding unnecessary PAL.

Soybean and Lupine Addition in Hen Nutrition-Influence on Egg Immunoreactivity.

Modifying hen fodder is a common way of changing eggs composition today. However, there is no information on the effect of the source of protein in the fodder replacement on egg allergenicity. This research aimed to detect potential differences in the immunoreactivity and protein composition of eggs from hens fed with fodder containing legume. The aim of the first step of the study was to select the proper solvent for extracting allergenic proteins from hen eggs. Two of them (containing Tween 20 and Triton 100) were selected, based on protein profile and concentration analysis. Egg-white- and egg-yolk-proteins extracts prepared with them were checked for potential differences, using SDS-PAGE electrophoresis, and then the Western-blot method, using sera from children allergic to eggs and soy. Preliminary studies on the influence of fodder composition on the composition of egg proteins suggest that the addition of soy and lupine to fodder modifies the expression of egg proteins. The observed differences in the immunoreactivity of proteins contained in hen egg-white samples do not seem to be as significant as the appearance of protein with a molecular weight of ~13 kDa in the yolk of eggs obtained from soybean-fed hens. This protein may increase the immunoreactivity of eggs for children allergic solely to soy.

A Preliminary Study on Cross-Reactivity of Heat-Treated Quail and Hen's Egg White Proteins in Young Children.

We investigated the effects of different types of heat treatments on hen's egg white (HEw) and quail egg white (QEw) proteins and their cross-reactivity in young children. Crude extracts of raw and water-boiled HEw and QEw and commercially developed stone-baked HEw were prepared. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was then performed. Patients diagnosed with HEw allergy were enrolled, and pooled sera were tested with each extract in an enzyme-linked immunosorbent assay (ELISA)-inhibition test. A skin prick test (SPT) and oral food challenge (OFC) were also performed. The median age of 12 patients was 2.5 years. SDS-PAGE results revealed strongly stained bands for the ovomucoid of boiled HEw and QEw, while stone-baked HEw displayed remarkable changes for all protein fractions. In the ELISA-inhibition test, pre-incubation of the sera led to a profound decrease, moderate decrease, and minimal decrease in the amount of IgE binding to boiled and raw HEw, boiled and raw QEw, and stone-baked HEw proteins, respectively. SPTs and OFC demonstrated cross-reactivity values of 41.7% (5/12) and 16.7% (2/12) for boiled QEw and stone-baked HEw, respectively. We observed moderate cross-reactivity between QEw and HEw. Boiling had a limited effect on altering egg allergenicity. Commercially developed, stone-baked HEw can be an alternative food for children with HE allergy.

Thermoneutrality Alters Gastrointestinal Antigen Passage Patterning and Predisposes to Oral Antigen Sensitization in Mice.

Food allergy is an emerging epidemic, and the underlying mechanisms are not well defined partly due to the lack of robust adjuvant free experimental models of dietary antigen sensitization. As housing mice at thermoneutrality (Tn) - the temperature of metabolic homeostasis (26-30°C) - has been shown to improve modeling various human diseases involved in inflammation, we tested the impact of Tn housing on an experimental model of food sensitization. Here we demonstrate that WT BALB/c mice housed under standard temperature (18-20°C, Ts) conditions translocated the luminal antigens in the small intestine (SI) across the epithelium via goblet cell antigen passages (GAPs). In contrast, food allergy sensitive Il4raF709 mice housed under standard temperature conditions translocated the luminal antigens in the SI across the epithelium via secretory antigen passages (SAPs). Activation of SI antigen passages and oral challenge of Il4raF709 mice with egg allergens at standard temperature predisposed Il4raF709 mice to develop an anaphylactic reaction. Housing Il4raF709 mice at Tn altered systemic type 2 cytokine, IL-4, and the landscape of SI antigen passage patterning (villus and crypt involvement). Activation of SI antigen passages and oral challenge of Il4raF709 mice with egg antigen under Tn conditions led to the robust induction of egg-specific IgE and development of food-induced mast cell activation and hypovolemic shock. Similarly, Tn housing of WT BALB/c mice altered the cellular patterning of SI antigen passage (GAPs to SAPs). Activation of SI antigen passages and the oral challenge of WT BALB/c mice with egg antigen led to systemic reactivity to egg and mast cell activation. Together these data demonstrate that Tn housing alters antigen passage cellular patterning and landscape, and concurrent oral exposure of egg antigens and SAP activation is sufficient to induce oral antigen sensitization.

Evaluation of the Immunogenic Response of a Novel Enterobactin Conjugate Vaccine in Chickens for the Production of Enterobactin-Specific Egg Yolk Antibodies.

Passive immunization with specific egg yolk antibodies (immunoglobulin Y, IgY) is emerging as a promising alternative to antibiotics to control bacterial infections. Recently, we developed a novel conjugate vaccine that could trigger a strong immune response in rabbits directed against enterobactin (Ent), a highly conserved siderophore molecule utilized by different Gram-negative pathogens. However, induction of Ent-specific antibodies appeared to be affected by the choice of animal host and vaccination regimen. It is still unknown if the Ent conjugate vaccine can trigger a specific immune response in layers for the purpose of production of anti-Ent egg yolk IgY. In this study, three chicken vaccination trials with different regimens were performed to determine conditions for efficient production of anti-Ent egg yolk IgY. Purified Ent was conjugated to three carrier proteins, keyhole limpet hemocyanin (KLH), bovine serum albumin (BSA) and CmeC (a subunit vaccine candidate), respectively. Intramuscular immunization of Barred Rock layers with KLH-Ent conjugate four times induced strong immune response against whole conjugate vaccine but the titer of Ent-specific IgY did not change in yolk with only a 4 fold increase detected in serum. In the second trial, three different Ent conjugate vaccines were evaluated in Rhode Island Red pullets with four subcutaneous injections. The KLH-Ent or CmeC-Ent conjugate consistently induced high level of Ent-specific IgY in both serum (up to 2,048 fold) and yolk (up to 1,024 fold) in each individual chicken. However, the Ent-specific immune response was only temporarily and moderately induced using a BSA-Ent vaccination. In the third trial, ten White Leghorn layers were subcutaneously immunized three times with KLH-Ent, leading to consistent and strong immune response against both whole conjugate and the Ent molecule in each chicken; the mean titer of Ent-specific IgY increased approximately 32 and 256 fold in serum and yolk, respectively. Consistent with its potent binding to various Ent derivatives, the Ent-specific egg yolk IgY also inhibited in vitro growth of a representative Escherichia coli strain. Together, this study demonstrated that the novel Ent conjugate vaccine could induce strong, specific, and robust immune response in chickens. The Ent-specific hyperimmune egg yolk IgY has potential for passive immune intervention against Gram-negative infections.

Effect of immunized egg proteins on the performance and neonatal diarrhoea incidence in newborn calves.

The aim of this study was to assess the effects of feeding immunized egg proteins (IEP) on the health and performance of newborn dairy calves. Sixty-four Holstein calves, both male and female, were divided over two treatments. Calves either received IEP or a placebo (PCB) in their colostrum and calf milk replacer (CMR) for the first 14 days of their life. Until day 49, CMR was offered at 15% of birth weight (BW), at 10% on days 49-57 and at 5% on days 57-63. In addition, calves received starter concentrate, chopped straw and water from 3 days old until 70 days old at the end of study. Individual CMR and concentrate intake were measured daily whilst BW was recorded weekly. Visual faecal scoring and health observations were conducted daily. Faecal samples were collected weekly up to 4 weeks and during the first 4 days of scouring to screen for presence of Cryptosporidium parvum, rotavirus, coronavirus, E. coli and Salmonella. Results indicated that feeding IEP increased BW (p < .05) at 42 and 56 days old, and BW also tended (p = .06) to be higher after weaning at 63-70 days old compared to the PCB group. When analysed using a repeated measures model, compared to feeding PCB, feeding IEP increased total concentrate consumption (p = .001) by 3.6kg/calf. Over the entire study, daily water intake was higher (p = .002) for the IEP group when compared with the PCB group. In the IEP group, 12 calves were scored as scouring whereas there were 14 calves in the PCB group. There were no significant differences between treatments in faecal pathogen load of neither healthy nor scouring calves. In conclusion, supplementing IEP during the first 14 days of calf life improved the performance of newborn calves. Further work is warranted to understand the mode of action of IEP in calves.

Integrative Transcriptomics Reveals Activation of Innate Immune Responses and Inhibition of Inflammation During Oral Immunotherapy for Egg Allergy in Children.

We previously reported the results of a randomized, open-label trial of egg oral immunotherapy (OIT) in 50 children where 44% were desensitized and 46% were partially desensitized after 8 months of treatment. Here we focus on cell-mediated molecular mechanisms driving desensitization during egg OIT. We sought to determine whether changes in genome-wide gene expression in blood cells during egg OIT correlate with humoral responses and the clinical outcome. The blood cell transcriptome of 50 children receiving egg OIT was profiled using peripheral blood mononuclear cell (PBMC) samples obtained at baseline and after 3 and 8 months of OIT. We identified 467 differentially expressed genes (DEGs) after 3 or 8 months of egg OIT. At 8 months, 86% of the DEGs were downregulated and played a role in the signaling of TREM1, IL-6, and IL-17. In correlation analyses, Gal d 1-4-specific IgG4 antibodies associated positively with DEGs playing a role in pathogen recognition and antigen presentation and negatively with DEGs playing a role in the signaling of IL-10, IL-6, and IL-17. Desensitized and partially desensitized patients had differences in their antibody responses, and although most of the transcriptomic changes were shared, both groups had also specific patterns, which suggest slower changes in partially desensitized and activation of NK cells in the desensitized group. OIT for egg allergy in children inhibits inflammation and activates innate immune responses regardless of the clinical outcome at 8 months. Changes in gene expression patterns first appear as posttranslational protein modifications, followed by more sustained epigenetic gene regulatory functions related to successful desensitization.

Plasma Proteome Responses in Salmonid Fish Following Immunization.

Vaccination plays a critical role in the protection of humans and other animals from infectious diseases. However, the same vaccine often confers different protection levels among individuals due to variation in genetics and/or immunological histories. While this represents a well-recognized issue in humans, it has received little attention in fish. Here we address this knowledge gap in a proteomic study of rainbow trout (Oncorhynchus mykiss, Walbaum), using non-lethal repeated blood sampling to establish the plasma protein response of individual fish following immunization. Six trout were immunized with adjuvanted hen egg-white lysozyme (HEL) and peripheral blood sampled at ten time points from day 0 to day 84 post-injection. We confirm that an antigen-specific antibody response to HEL was raised, showing differences in timing and magnitude among individuals. Using label-free liquid chromatography-mass spectrometry, we quantified the abundance of 278 plasma proteins across the timecourse. As part of the analysis, we show that this approach can distinguish many (but not all) duplicated plasma proteins encoded by paralogous genes retained from the salmonid-specific whole genome duplication event. Global variation in the plasma proteome was predominantly explained by individual differences among fish. However, sampling day explained a major component of variation in abundance for a statistically defined subset of 41 proteins, representing 15% of those detected. These proteins clustered into five groups showing distinct temporal responses to HEL immunization at the population level, and include classical immune (e.g. complement system members) and acute phase molecules (e.g. apolipoproteins, haptoglobins), several enzymes and other proteins supporting the immune response, in addition to evolutionarily conserved molecules that are as yet uncharacterized. Overall, this study improves our understanding of the fish plasma proteome, provides valuable marker proteins for different phases of the immune response, and has implications for vaccine development and the design of immune challenge experiments.

Phenotypes and natural history of food protein-induced enterocolitis syndrome in the east Mediterranean region.

Background: Food protein-induced enterocolitis syndrome (FPIES) is a rare non-IgE mediated food allergy. Objective: To delineate the differences in the spectrum of culprit foods, remission patterns, and predictors among varying cultures. Methods: We reviewed demographics, culprit foods, outcomes, and predictors in 81 children with a diagnosis of FPIES who were followed up between 2015 and 2020. Results: Eighty-one patients (55.6% boys) were enrolled, including 72 with acute FPIES and 9 with chronic FPIES. Hen's egg was the most common culprit food (36.6%), followed by fish (26.9%), and cow's milk (21.5%). Interestingly, cow's milk was significantly prevalent in chronic FPIES cases (p = 0.006). The most common clinical symptoms were vomiting (100%), pallor (63.4%), and lethargy (55.9%). Emergency department visits were noted in 39 patients (41.9%), of whom 37 (39.8%) were treated with intravenous (IV) fluid. The subjects were followed up for a median (interquartile range) of 19.4 months (12.3-41.2 months), and 26 subjects (32.1%) achieved tolerance. The median (interquartile range) age at tolerance was 2.5 years (2.1-3.2 years). With regard to the culprit foods, hen's egg was observed more frequently in the subjects with resolved FPIES cases (p = 0.008), whereas fish FPIES cases were high in the persistent group (p = 0.001). IgE sensitization of the culprit food was found to be an independent risk factor for the persistence of FPIES (odds ratio 4.855 [95% confidence interval, 1.131-20.844]; p = 0.034). Conclusion: In our cohort, unlike other published series, hen's egg and fish were the two most common culprit foods. Fish differed from other culprit foods, with significantly delayed onset and persistence, and may create a model that allows for the understanding of the disease.

Inhalation challenge test using pigeon eggs for chronic hypersensitivity pneumonitis.

BACKGROUND: Chronic hypersensitivity pneumonitis (CHP) remains a diagnostic challenge. The process of collecting and extracting serum and droppings from causative animals for the inhalation challenge test is complicated and the risk of inducing disease progression exists. OBJECTIVE: To investigate the utility and safety of an inhalation challenge test using pigeon eggs. METHODS: Pigeon eggs were pasteurized and mixed with a saline solution to produce an inhalation fluid. An inhalation challenge test was conducted on 19 patients with bird-related CHP and 17 patients with interstitial lung disease other than bird-related CHP. To identify antigens in pigeon eggs, the antigen-antibody responses of the pigeon eggs and serum from patients were evaluated using Western blotting. RESULTS: The mean changes in C-reactive protein, alveolar-arterial oxygen difference, erythrocyte sedimentation rate, and lactate dehydrogenase significantly increased by 0.32 mg/dL (P = .014), 7.8 Torr (P = .002), 1.4 mm/h (P = .012), and 5.4 U/mL (P = .0019), respectively, in bird-related CHP group compared to the control 24 hours after the inhalation challenge test. Furthermore, within 24 hours of the inhalation test, the mean forced vital capacity decreased by 2.3% in the bird-related CHP group compared with a decline of 0.05% in the control group (P = .035). Serum collected from seven bird-related CHP patients who underwent the inhalation challenge test and reacted to antigens with molecular weights of 37-75 KDa, and these molecular weights were consistent with egg albumin and globulin. CONCLUSION: Since a mild response was observed after the inhalation challenge test using pigeon eggs, this test was an obvious candidate for diagnosing bird-related CHP.

Detection of specific IgE against linear epitopes from Gal d 1 has additional value in diagnosing hen's egg allergy in adults.

BACKGROUND: Although hen's egg allergy is more prevalent in children, up to 0.6% of adults from different European countries suffer from a persistent or newly onset hen's egg allergy, making accurate diagnosis in adults necessary. However, sensitization to hen's egg extracts, components and linear epitopes is solely studied in children. METHODS: Hen's egg allergic (n = 16) and tolerant (n = 19) adults were selected by sensitization towards recombinant components rGal d 1 and/or 3. Sensitization profiles towards egg white and yolk extract and the native components Gal d 1, 2, 3 and 4 were respectively evaluated with the ImmunoCAP or the EUROLINE system. Characterization of linear epitopes was performed with a peptide microarray containing 15mer peptides representing the entire sequence of mature Gal d 1 and 3. RESULTS: Overall, sIgE titres against hen's egg extracts and single components overlapped largely between allergic and tolerant adults. Although the median sIgE/sIgG4 ratio to Gal d 1 was increased in allergic adults, the range was comparable between both groups. Clinically relevant sensitization to Gal d 1 was confirmed by sIgE-binding to the linear epitopes aa30-41, aa39-50 or aa84-95 in 6/13 allergic adults, mainly suffering from objective symptoms. In comparison, these epitopes were recognized by 1/15 tolerant patient. Only a few linear epitopes were detected for Gal d 3, suggesting a greater importance of conformational epitopes for the recognition of Gal d 3. CONCLUSION AND CLINICAL RELEVANCE: Specific IgE-binding to linear epitopes of Gal d 1 is highly specific in identifying hen's egg allergic adults with objective symptoms.

Vitellogenin receptor expression in ovaries controls innate immunity in the Chinese mitten crab (Eriocheir sinensis) by regulating vitellogenin accumulation in the hemolymph.

The vitellogenin receptor (Vgr), which is specific for vitellogenin (Vtg), recognises and transports Vtg into the ovaries. Accumulating evidence suggests that Vtg also performs an immune defence function and plays critical roles in innate immunity in oviparous animals. However, whether Vgr is involved in innate immunity in the Chinese mitten crab (Eriocheir sinensis) is unknown. In this study, we obtained a 3009 nucleotide partial cDNA of the E. sinensis vitellogenin receptor gene (Es-vgr) encoding an open reading frame of 1003 amino acid residues. Bioinformatics analysis showed that the domains of Es-vgr were conserved during evolution. Quantitative real-time PCR and western blotting revealed that the highest Es-vgr expression levels occurred in the ovary, and expression was specific. Comparison of the expression levels of Es-vgr and the Vtg gene (Es-vtg1) at different ovary developmental stages suggested that there may be some regulatory relationship between them. Bacterial challenge induced high-level expression of antimicrobial peptide genes and reduced Es-vgr expression in ovaries, resulting in massive accumulation of Vtg in the hemolymph. The survival rate of crabs increased significantly after injection with recombinant Es-vtg1 protein following bacterial infection. Collectively, these results demonstrate that Es-vgr plays critical roles in antimicrobial function by regulating the accumulation of Vtg in the hemolymph.

Can food processing produce hypoallergenic egg?

Eggs and their derived products are common foods that can induce food allergic reaction, especially in children. The reported incidence of egg allergy is 1% to 2%, and its prevalence has rapidly increased in recent years. Currently, there is no approved treatment for it. The clinical guidance for this adverse food reaction is the complete elimination of egg (and their derived products) from diet, which is difficult due to the wide use of egg ingredients in food industry. Food processing methods can affect the conformational and/or linear epitopes of allergens and may change the allergenicity of egg. Thermal treatment and various other processing methods based on the enzymatic hydrolysis and irradiation have been found useful in reducing allergenicity of certain egg allergens. However, processed egg proteins can also show an increased allergenicity after treatment and the correct pattern to follow for the generation of hypoallergenic products remains unclear. This review explores the influence of processing methods on egg allergenicity and reports the best options for the generation of hypoallergenic egg products to date.

Effect of enzyme immobilization and in vitro digestion on the immune-reactivity and sequence of IgE epitopes in egg white proteins.

The effects of hydrolysis by free and immobilized forms of Neutrase (FN, IN, respectively) and Thermolysin (FT, IT, respectively) and in vitro digestion on the degree of hydrolysis (DH) of egg white proteins, molecular weight distribution of peptides, immune-reactivity and IgE epitopes of egg white proteins were investigated. With FT and IT in the intestinal digests, the proteolysis followed by in vitro digestion produced peptides smaller than 10 kDa. Hydrolysis with the immobilized enzymes had a greater effect than the free enzymes on increasing surface hydrophobicity. The lowest IgE-binding capacity was observed for the intestinal digest of IT-derived hydrolysates (3.3 ± 1.9%). Compared to in vitro digestion, proteolysis showed a significant effect on the immune-reactivity reduction of egg white proteins. Liquid chromatography-tandem mass spectrometry data showed that the most resistant epitopes to enzymatic hydrolysis and in vitro digestion were in ovomucoid, where epitope fragments 1-10, 1-14, 1-20, 4-20, 11-20, 61-74, 71-75 and 101-105 remained intact. Overall, the IgE-binding capacities of egg white proteins were not completely removed after the enzymatic hydrolysis and in vitro digestion due to the presence of intact proteins such as lysozyme and also due to the several immunoreactive peptides derived from egg white proteins.

Egg Allergy: Diagnosis and Immunotherapy.

Hypersensitivity or an allergy to chicken egg proteins is a predominant symptomatic condition affecting 1 in 20 children in Australia; however, an effective form of therapy has not yet been found. This occurs as the immune system of the allergic individual overreacts when in contact with egg allergens (egg proteins), triggering a complex immune response. The subsequent instantaneous inflammatory immune response is characterized by the excessive production of immunoglobulin E (IgE) antibody against the allergen, T-cell mediators and inflammation. Current allergen-specific approaches to egg allergy diagnosis and treatment lack consistency and therefore pose safety concerns among anaphylactic patients. Immunotherapy has thus far been found to be the most efficient way to treat and relieve symptoms, this includes oral immunotherapy (OIT) and sublingual immunotherapy (SLIT). A major limitation in immunotherapy, however, is the difficulty in preparing effective and safe extracts from natural allergen sources. Advances in molecular techniques allow for the production of safe and standardized recombinant and hypoallergenic egg variants by targeting the IgE-binding epitopes responsible for clinical allergic symptoms. Site-directed mutagenesis can be performed to create such safe hypoallergens for their potential use in future methods of immunotherapy, providing a feasible standardized therapeutic approach to target egg allergies safely.

The frequency of cross-reactivity with various avian eggs among children with hen's egg allergy using skin prick test RESULTS: fewer sensitizations with pigeon and goose egg

INTRODUCTION AND OBJECTIVES: A high rate of cross-reactivity has been reported between the specific proteins of hen's egg with proteins of various avian eggs by quantitative immunoelectrophoretic techniques. The aim of this study was to assess the clinical cross-reactivity of different birds' eggs in children with hen's egg allergy based on skin prick test results. MATERIAL AND METHODS: This cross-sectional study enrolled 52 infants with hen's egg allergy and 52 healthy infants with no history of food allergy from October 2018 to April 2019. Skin prick tests were performed in both patient and control groups with fresh extract of white and yolk related to pigeon, duck, goose, turkey, quail, and partridge. RESULTS: Fifty (96.1%) children with hen's egg allergy showed positive sensitization to at least one of the avian eggs. The most frequent positive skin tests were related to quail's white (36 = 69.2%) followed by duck's white (34 = 65.5%), and sensitization was the least frequent in pigeon's yolk (23 = 44.2%). Skin tests of the control group were negative to all the tested extracts. CONCLUSIÓN: Because of fewer sensitizations to some avian eggs, further research should clarify starting oral immunotherapy with the yolk of goose and pigeon in children with hen's egg allergy

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Influence of heat treatment and egg matrix on the physicochemical and allergenic properties of egg custard.

To investigate the influence of heat treatment and egg matrix on egg custard (EC) proteins, 12 different kinds of ECs with different egg/water ratios (1:1, 1:1.5, 1:2, or 1:3, v/v) and different heating temperatures (80, 90, or 100 °C) and times (10, 15, or 20 min) were prepared and evaluated for the digestibility, structure, eliciting capacity and sensitizing capacity using SDS-PAGE, fluorescence spectra, ELISA, and a BALB/c mouse model, respectively. The physicochemical properties of EC proteins were significantly affected by heat treatment and egg matrix, which showed the increased digestibility and partially unfolded structure. The eliciting capacity of EC evaluated by IgE binding to sera from egg-allergic patients was reduced after heat treatment, and the EC made by heating at 100 °C for 20 min with a whole egg/water ratio of 1:2 (v/v) was the weakest. The sensitizing capacity of EC was also reduced in the BALB/c mouse model, which showed the significantly decreased levels of specific IgE, IgG, IgG1 and IgG2a, mMCP-1 and histamine in the mouse sera, as well as cytokine secretions of IL-4, IL-5, and IL-13, compared with the raw egg (RE) group. Results demonstrate that heat treatment and egg matrix significantly reduced the eliciting and sensitizing capacity of EC by changing the tertiary structure and increasing the digestibility of EC proteins. PRACTICAL APPLICATION: Egg custard (EC) is one kind of savory food suitable for all ages, and is also a traditional supplementary food for infants and young children in China. However, limited information is available on the allergenicity of egg custard. In this work, we evaluated how the structure, digestibility, and allergenic potential of egg allergens in EC were altered by the degree of thermal treatment and egg matrix, and elucidated the links between the physicochemical properties and allergenic potential of EC affected by heat treatment and egg matrix. Our results demonstrate that heat treatment and egg matrix significantly reduced the eliciting and sensitizing capacity of EC by changing the tertiary structure and increasing the digestibility of EC proteins.