Strategies for converting allergens into hypoallergenic vaccine candidates

Specific immunotherapy is based on the administration of increasing doses of allergens to allergic patients with the aim of inducing a state of antigen-specific unresponsiveness. Specific immunotherapy is one of the few causative treatment approaches for Type I allergy but may cause numerous side effects, including local inflammatory reactions, systemic manifestations (e.g., asthma attacks) and in the worst case, anaphylactic shock which may lead to death. Several attempts have been made in the past to reduce the rate of side effects. They included the chemical modification of allergen extracts to reduce their allergenic activity and the adsorption of allergen extracts to adjuvants to prevent the systemic release of allergens after administration. During the last decade, cDNAs coding for the most relevant allergens have been isolated and the corresponding allergens have been produced as recombinant molecules. Using allergen-encoding cDNAs, the amino acid sequence of allergens or purified recombinant allergens several strategies can now be applied to produce allergen derivatives with reduced allergenic activity for allergy vaccination in a controlled and reproducible manner. Currently, allergen-encoding cDNAs are used to engineer recombinant hypoallergenic allergen derivatives. According to the amino acid sequences and experimental epitope mapping data, synthetic peptides representing T- or B-cell epitopes are produced and purified recombinant allergens are coupled to novel adjuvants for vaccine formulation. In this article, strategies for the production and evaluation of allergen derivatives with reduced allergenic activity for allergy vaccination are described. These new vaccines hold great promise to improve the current practice of allergen-specific immunotherapy and maybe also used for prophylactic vaccination in the future.     

Genetically engineered and synthetic allergen derivatives: candidates for vaccination against type I allergy.

Type I allergy, a hypersensitivity disease affecting almost 20% of the population worldwide, is based on the IgE recognition of otherwise harmless antigens (i.e., allergens). Allergen-induced crosslink of effector cell-bound IgE antibodies leads to the release of biological mediators and thus to immediate disease symptoms (allergic rhinitis, conjunctivitis and asthma). Specific immunotherapy, the only causative treatment of Type I allergy, is based on the administration of increasing doses of allergens to allergic patients in order to yield allergen-specific non-responsiveness. Major disadvantages are 1. that current forms of allergen immunotherapy are performed with allergens difficult to standardize which cannot be matched to the patients reactivity profile and 2. that the administration of active allergen preparations can cause anaphylactic side effects. Through the application of molecular biological techniques many relevant environmental allergens have been produced as active recombinant proteins which allow component-resolved allergy diagnosis and thus represent the basis for patient-tailored forms of immunotherapy. Here we review molecular strategies which have been recently applied to generate genetically engineered and synthetic hypoallergenic allergen derivatives for patient-tailored and safe vaccination against Type I allergy.     

B cell epitopes of the major timothy grass pollen allergen, phl p 1, revealed by gene fragmentation as candidates for immunotherapy.

Group 1 grass pollen allergens are recognized by IgE antibodies of almost 40% of allergic individuals and therefore belong to the most important elicitors of Type I allergy worldwide. We have previously isolated the cDNA coding for the group 1 allergen from timothy grass, Phl p 1, and demonstrated that recombinant Phl p 1 contains most of the B cell as well as T cell epitopes of group 1 allergens from a variety of grass and corn species. Here we determine continuous B cell epitopes of Phl p 1 by gene fragmentation. IgE antibodies of grass pollen allergic patients identified five continuous epitope-containing areas that on an average bound 40% of Phl p 1-specific IgE antibodies and were stably recognized in the course of disease. In contrast to untreated patients, patients undergoing grass pollen immunotherapy started to mount IgG(4) antibodies to the recombinant IgE-defined fragments in the course of immunotherapy. The protective role of these IgG(4) antibodies is demonstrated by observations that 1) increases in rPhl p 1 fragment-specific IgG(4) were in parallel with decreases in Phl p 1-specific IgE, and 2) preincubation of rPhl p 1 with patients sera containing rPhl p 1 fragment-specific IgG(4) blocked histamine release from basophils of an untreated grass pollen allergic patient. We propose to use recombinant Phl p 1 fragments for active immunotherapy in order to induce protective IgG responses against IgE epitopes in grass pollen allergic patients. This concept may be applied for the development of allergy vaccines whenever the primary sequence or structure of an allergen is available.     

Specific hyposensitization of microbial allergy by using a synthetic artificial polyelectrolyte

In this work the effectiveness of complex immunotherapy, including specific inhalation hyposensitization with the introduction of artificial synthetic polyelectrolite, was studied. Specific allergen produced a good effect (75%) in the inhalation hyposensitization of hemophilic allergy. The intramuscular injection of artificial synthetic polyelectrolite, made in addition to the inhalation of allergen, produced a better desensitizing effect than the separate administration of allergen or polyelectrolite. The multiple administration of polyelectrolite produced a desensitizing effect on allergic reactions of type I with the tendency towards the decrease of reactions of type IV. Good prospects for the development of methods for special treatment with homologous allergen in combination with NA-5 in cases of microbial sensitization under the control of immunocompetent cells were shown.     

Oral administration of ovalbumin after sensitization attenuates symptoms in a mouse model of food allergic enteropathy

Oral immunotherapy (OIT) is a promising treatment of food allergy. To administer an appropriate oral dose of an allergenic component as OIT to individuals sensitized with a food allergen may prevent inducing food allergic inflammation in them. So we attempted to establish a mouse model to evaluate efficacy for oral administration of food allergen after sensitization. In BALB/c mice sensitized by injecting ovalbumin (OVA) with alum twice, OVA was administered before inducing inflammation by feeding the mice with egg white (EW) diet. Severe inflammatory responses, such as enteropathy, weight loss, IL-4 production, and increase of IgE antibody levels, were suppressed by administration with 4 mg of OVA 7 times before feeding EW diet. OVA administration alone induced a slight Th2 response, but no symptoms. The current study demonstrated that severe food allergic enteropathy could be prevented by pre-administration with appropriate dose of OVA to sensitized mice.     

Greater risk of incident asthma cases in adults with Allergic Rhinitis and Effect of Allergen Immunotherapy: A Retrospective Cohort Study

Asthma and rhinitis are often co-morbid conditions. As rhinitis often precedes asthma it is possible that effective treatment of allergic rhinitis may reduce asthma progression.The aim of our study is to investigate history of allergic rhinitis as a risk factor for asthma and the potential effect of allergen immunotherapy in attenuating the incidence of asthma.Hospital-referred non-asthmatic adults, aged 18–40 years between 1990 and 1991, were retrospectively followed up until January and April 2000. At the end of follow up, available subjects were clinically examined for asthma diagnosis and history of allergen specific immunotherapy, second-hand smoking and the presence of pets in the household. A total of 436 non-asthmatic adults (332 subjects with allergic rhinitis and 104 with no allergic rhinitis nor history of atopy) were available for final analyses.The highest OR (odds ratio) associated with a diagnosis of asthma at the end of follow-up was for the diagnosis of allergic rhinitis at baseline (OR, 7.8; 95%CI, 3.1–20.0 in the model containing the covariates of rhinitis diagnosis, sex, second-hand smoke exposure, presence of pets at home, family history of allergic disorders, sensitization to Parietaria judaica; grass pollen; house dust mites; Olea europea: orchard; perennial rye; and cat allergens). Female sex, sensitization to Parietaria judaica and the presence of pets in the home were also significantly predictive of new onset asthma in the same model. Treatment with allergen immunotherapy was significantly and inversely related to the development of new onset asthma (OR, 0.53; 95%CI, 0.32–0.86).In the present study we found that allergic rhinitis is an important independent risk factor for asthma. Moreover, treatment with allergen immunotherapy lowers the risk of the development of new asthma cases in adults with allergic rhinitis.     

Functional analysis of birch pollen allergen Bet v 1-specific regulatory T cells

Allergen-specific immunotherapy using peptides is an efficient treatment for allergic diseases. Recent studies suggest that the induction of CD4+ regulatory T (Treg) cells might be associated with the suppression of allergic responses in patients after allergen-specific immunotherapy. Our aim was to identify MHC class II promiscuous T cell epitopes for the birch pollen allergen Bet v 1 capable of stimulating Treg cells with the purpose of inhibiting allergic responses. Ag-reactive CD4+ T cell clones were generated from patients with birch pollen allergy and healthy volunteers by in vitro vaccination of PBMC using Bet v 1 synthetic peptides. Several CD4+ T cell clones were induced by using 2 synthetic peptides (Bet v 1(141-156) and Bet v 1(51-68)). Peptide-reactive CD4+ T cells recognized recombinant Bet v 1 protein, indicating that these peptides are produced by the MHC class II Ag processing pathway. Peptide Bet v 1(141-156) appears to be a highly MHC promiscuous epitope since T cell responses restricted by numerous MHC class II molecules (DR4, DR9, DR11, DR15, and DR53) were observed. Two of these clones functioned as typical Treg cells (expressed CD25, GITR, and Foxp3 and suppressed the proliferation and IL-2 secretion of other CD4+ T cells). Notably, the suppressive activity of these Treg cells required cell-cell contact and was not mediated through soluble IL-10 or TGF-beta. The identified promiscuous MHC class II epitope capable of inducing suppressive Treg responses may have important implication for the development of peptide-based Ag-specific immunotherapy to birch pollen allergy.     

Calcium-dependent immunoglobulin E recognition of the apo- and calcium-bound form of a cross-reactive two EF-hand timothy grass pollen allergen, Phl p 7.

Type I allergy, an immunodisorder that affects almost 20% of the population worldwide, is based on the immunoglobulin E (IgE) recognition of per se innocuous antigens (allergens). Pollen from wind-pollinated plants belong to the most potent allergen sources. We report the isolation of a cDNA coding for a 8.6 kDa two EF-hand calcium binding allergen, Phl p 7, from a timothy grass (Phleum pratense) pollen expression cDNA library, using serum IgE from a grass pollen allergic patient. Sequence analysis identified Phl p 7 as a member of a recently discovered subfamily of pollen-specific calcium binding proteins. Recombinant Phl p 7 was expressed in Escherichia coli and purified to homogeneity as determined by mass spectroscopy. Approximately 10% of pollen allergic patients displayed IgE reactivity to rPhl p 7 and Phl p 7-homologous allergens present in pollens of monocotyledonic and dicotyledonic plants. Circular dichroism analysis of the calcium-bound and apo-rPhl p 7 indicated that differences in IgE recognition may be due to calcium-induced changes in the protein conformation. The fact that patients mount IgE antibodies against different protein conformations is interpreted as a footprint of a preferential sensitization against either form. The biological activity of rPhl p 7 was demonstrated by its ability to induce basophil histamine release and immediate type skin reactions in sensitized individuals. In conclusion, IgE binding to Phl p 7 represents an example for the conformation-dependent IgE recognition of an allergen. Recombinant Phl p 7 may be used for diagnosis and perhaps treatment of a group of patients who suffer from allergy to pollens of many unrelated plant species.     

Proteomics and immunological analysis of a novel shrimp allergen,Pen m 2

Shellfish are a common cause of adverse food reactions in hypersensitive individuals and shrimp is one of the most frequently reported causes of allergic reactions. A novel allergen from Penaeus monodon, designated Pen m 2, was identified by two-dimensional immunoblotting using sera from subjects with shrimp allergy, followed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry analysis of the peptide digest. This novel allergen was then cloned and the amino acid sequence deduced from the cDNA sequence. The cloned cDNA encoded a 356-aa protein with an acetylated N terminus at Ala2, identified by postsource decay analysis. Comparison of the Pen m 2 sequence with known protein sequences revealed extensive similarity with arginine kinase (EC 2.7.3.3) from crustaceans. Pen m 2 was purified by anion exchange chromatography and shown to have arginine kinase activity and to react with serum IgE from shrimp allergic patients and induce immediate type skin reactions in sensitized patients. Using Pen m 2-specific antisera and polyclonal sera from shrimp-sensitive subjects in a competitive ELISA inhibition assay, Pen m 2 was identified as a novel cross-reactive Crustacea allergen. This novel allergen could be useful in allergy diagnosis and in the treatment of Crustacea-derived allergic disorders.     

Preventive actions of allergen immunotherapy: the facts and the effects in search of evidence

Allergen immunotherapy (AIT) is the only treatment that works on the causes of allergy. Available AIT nowadays are subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT) for allergic rhinitis and asthma, while for allergy to Hymenoptera venom only subcutaneous route is recommended. A bulk of trials and meta-analyses demonstrated that efficacy and safety of AIT in decreasing allergic clinical symptoms and use of rescue medications, while its preventive capacity is yet under investigation. The most important of these effects is the prevention of potentially fatal anaphylactic reactions to Hymenoptera stings by venom immunotherapy (VIT). A certain number of studies thus far available showed that AIT, in both forms, is able to prevent the progress of allergic rhinitis into asthma and the development of new sensitizations. These effects should be related to the mechanisms of action of AIT. In fact, it has been demonstrated that both SCIT and SLIT are able to modify the allergen presentation by dendritic cells, with result in modification of the phenotype of allergen-specific T cells, switching from the typical of allergic inflammation Th2-type response to a Th1-type one. Also allergen-specific T regulatory (Treg) cells play a pivotal role by producing suppressive cytokines, such as IL-10 and TGF-beta. However, the only plain evidence of a preventive effect concerns VIT, while the other outcomes need to be furtherly investigated.     

The future of antigen-specific immunotherapy of allergy

More than 25% of the population in industrialized countries suffers from immunoglobulin-E-mediated allergies. The antigen-specific immunotherapy that is in use at present involves the administration of allergen extracts to patients with the aim to cure allergic symptoms. However, the risk of therapy-induced side effects limits its broad application. Recent work indicates that the epitope complexity of natural allergen extracts can be recreated using recombinant allergens, and hypoallergenic derivatives of these can be engineered to increase treatment safety. It is proposed that these modified molecules will improve the current practice of specific immunotherapy and form a basis for prophylactic vaccination.     

Specific IgE response to different grass pollen allergen components in children undergoing sublingual immunotherapy

ABSTRACT: BACKGROUND: Grass pollen is a major cause of respiratory allergy worldwide and contain a number of allergens, some of them (Phl p 1, Phl p 2, Phl p 5, and Phl 6 from Phleum pratense, and their homologous in other grasses) are known as major allergens. The administration of grass pollen extracts by immunotherapy generally induces an initial rise in specific immunoglobulin E (sIgE) production followed by a progressive decline during the treatment. Some studies reported that immunotherapy is able to induce a de novo sensitisation to allergen component previously unrecognized. METHODS: We investigated in 30 children (19 males and 11 females, mean age 11.3 years), 19 treated with sublingual immunotherapy (SLIT) by a 5-grass extract and 11 untreated, the sIgE and sIgG4 response to the different allergen components. RESULTS: Significant increases ( p < 0.001) were detected for Phl p 1, Phl p 2, Phl p 5, and Phl p 6, while sIgE levels induced in response to Phl p 7 and Phl p 12 were low or absent at baseline and unchanged following SLIT treatment; no new sensitisation was detected. As to IgG4, significant increases were found for Phl p2 and Phl p 5, while the increase for Phl p 12 was not significant. In the control group, no significant increase in sIgE for any single allergen component was found. CONCLUSIONS: These findings confirm that the initial phase of SLIT with a grass pollen extract enhances the sIgE synthesis and show that the sIgE response concerns the same allergen components which induce IgE reactivity during natural exposure.     

Adverse reactions to foods

Allergic reactions to foods represent a prominent, actual and increasing problem in clinical medicine. Symptoms of food allergy comprise skin reactions (urticaria, angioedema, eczema) respiratory (bronchoconstriction, rhinitis), gastrointestinal (cramping, diarrhea) and cardiovascular symptoms with the maximal manifestation of anaphylactic shock. They can be elicited by minute amounts of allergens. The diagnosis of food allergy is done by history, skin test, in vitro allergy diagnosis and — if necessary — oral provocation tests, if possible placebo-controlled. Avoidance of respective allergens for the allergic patient, however, is often complicated or impossible due to deficits in declaration regulations in many countries. Increasing numbers of cases including fatalities, due to inadvertent intake of food allergens are reported. It is therefore necessary to improve declaration laws and develop methods for allergen detection in foods. Allergens can be detected by serological methods (enzyme immunoassays, in vitro basophil histamine release or in vivo skin test procedures in sensitized individuals). The problem of diagnosis of food allergy is further complicated by cross-reactivity between allergens in foods and aeroallergens (pollen, animal epithelia, latex etc.). Elicitors of pseudo-allergic reactions with similar clinical symptomatology comprise low-molecular-mass chemicals (preservatives, colorings, flavor substances etc.). For some of them (e.g. sulfites) detection assays are available. In some patients classic allergic contact eczema can be elicited systemically after oral intake of low-molecular-mass contact allergens such as nickel sulfate or flavorings such as vanillin in foods. The role of xenobiotic components in foods (e.g. pesticides) is not known at the moment. In order to improve the situation of the food allergic patient, research programs to elucidate the pathophysiology and improve allergen detection strategies have to be implemented together with reinforced declaration regulations on a quantitative basis.     

Impact of Dermatophagoides pteronyssinus mite body raw material on house dust mite allergy diagnosis in a Serbian population

House dust mite (HDM) allergy has different clinical and immunological patterns in different geographic regions. The impact of raw material of commercial Dermatophadoides pteronyssinus (Acari: Pyroglyphidae) mite bodies on the quality of allergen extracts for allergy diagnosis in the Serbian population has not been previously evaluated. House dust mite bodies obtained from manufacturers in Europe, South America and Australia were used in the preparation of allergen extracts for in vivo diagnosis and serological analysis in a group of 14 HDM‐allergic adults. In the group of mite‐allergic patients, there was no statistically significant difference in skin test reactivity (Wilcoxon matched pairs test) among the three HDM body extract preparations. In a CAP inhibition assay, two extracts (A and C) achieved maximum inhibition of >90%, whereas extract B demonstrated a different inhibition slope and lower inhibition potential (80%). However, a remarkable difference in immunoglobulin E reactivity using Western blot analysis with individual patients' sera was observed in one of the preparations (extract B). These findings emphasize the need for the careful selection of starting material for the preparation of HDM diagnostic reagents intended for use in patients from geographically distinct regions as these preparations can have implications on the selection criteria for patient‐tailored immunotherapy of HDM allergy.     

T cell epitope-containing hypoallergenic recombinant fragments of the major birch pollen allergen, Bet v 1, induce blocking antibodies

Allergen-specific immunotherapy represents one of the few curative approaches toward type I allergy. Up to 25% of allergic patients are sensitized against the major birch pollen allergen, Bet v 1. By genetic engineering we produced two recombinant (r) Bet v 1 fragments comprising aa 1-74 and aa 75-160 of Bet v 1, which, due to a loss of their native-like fold, failed to bind IgE Abs and had reduced allergenic activity. Here we show that both fragments covering the full Bet v 1 sequence induced human lymphoproliferative responses similar to rBet v 1 wild type. The C-terminal rBet v 1 fragment induced higher lymphoproliferative responses than the N-terminal fragment and represented a Th1-stimulating segment with high IFN-gamma production, whereas the N-terminal fragment induced higher IL-4, IL-5, and IL-13 secretion. Immunization of mice and rabbits with rBet v 1 fragments induced IgG Abs, which cross-reacted with complete Bet v 1 and Bet v 1-related plant allergens and strongly inhibited the IgE binding of allergic patients to these allergens. Thus, our results demonstrate that hypoallergenic T cell epitope-containing rBet v 1 fragments, despite lacking IgE epitopes, can induce Abs in vivo that prevent the IgE binding of allergic patients to the wild-type allergen. The overall demonstration of the immunogenic features of the hypoallergenic rBet v 1 fragments will now enable clinical studies for safer and more efficient specific immunotherapy.     

Graph Based Study of Allergen Cross-Reactivity of Plant Lipid Transfer Proteins (LTPs) Using Microarray in a Multicenter Study

The study of cross-reactivity in allergy is key to both understanding. the allergic response of many patients and providing them with a rational treatment In the present study, protein microarrays and a co-sensitization graph approach were used in conjunction with an allergen microarray immunoassay. This enabled us to include a wide number of proteins and a large number of patients, and to study sensitization profiles among members of the LTP family. Fourteen LTPs from the most frequent plant food-induced allergies in the geographical area studied were printed into a microarray specifically designed for this research. 212 patients with fruit allergy and 117 food-tolerant pollen allergic subjects were recruited from seven regions of Spain with different pollen profiles, and their sera were tested with allergen microarray. This approach has proven itself to be a good tool to study cross-reactivity between members of LTP family, and could become a useful strategy to analyze other families of allergens.     

Molecular and immunological characterization of arginine kinase from the Indianmeal moth, Plodia interpunctella, a novel cross-reactive invertebrate pan-allergen.

IgE recognition of indoor allergens represents a major cause of allergic asthma in atopic individuals. We found that 52 of 102 patients suffering from allergic symptoms indoors contained IgE Abs against allergens from the Indianmeal moth (Plodia interpunctella), a ubiquitous food pest. Using serum IgE from a moth-sensitized patient we screened an expression cDNA library constructed from P. interpunctella larvae. cDNAs coding for arginine kinase (EC 2.7.3.3), a 40-kDa enzyme commonly occurring in invertebrates that is involved in the storage of such high-energy phosphate bonds as phosphoarginine, were isolated. Recombinant moth arginine kinase, designated Plo i 1, was expressed in Escherichia coli as a histidine-tagged protein with enzymatic activity, and purified to homogeneity by nickel chelate affinity chromatography. Purified recombinant arginine kinase induced specific basophil histamine release and immediate as well as late-phase skin reactions. It reacted with serum IgE from 13 of the 52 (25%) moth-allergic patients and inhibited the binding of allergic patients' IgE to an immunologically related 40-kDa allergen present in house dust mite, cockroach, king prawn, lobster, and mussel. Our results indicate that arginine kinases represent a new class of cross-reactive invertebrate pan-allergens. Recombinant arginine kinase may be used to identify a group of polysensitized indoor allergic patients and for immunotherapy of these individuals.     

The Anisakis allergy debate: does an evolutionary approach help?

Allergic phenomena share common pathways with the immune response against helminth parasites. The definitions regarding allergens and their related concepts have their roots in the area of allergy research. The experience with the fish parasite Anisakis simplex-associated allergic features still nurtures an open debate on the necessity of larvae being alive to induce allergic reactions such as urticaria or anaphylaxis. Conceptual definitions of allergen, major allergen, as well as putatively crossreacting antibodies, as are used in food allergy, depend on the clinical relevance of specific IgE and deserve careful interpretation in the various forms of A. simplex-associated allergic features. Conversely, an evolutionary based interpretation of the presence of specific IgE depends on the viability of A. simplex.     

Analysis of epitope-specific immune responses induced by vaccination with structurally folded and unfolded recombinant Bet v 1 allergen derivatives in man

Previously, we have constructed recombinant derivatives of the major birch pollen allergen, Bet v 1, with a more than 100-fold reduced ability to induce IgE-mediated allergic reactions. These derivatives differed from each other because the two recombinant Bet v 1 fragments represented unfolded molecules whereas the recombinant trimer resembled most of the structural fold of the Bet v 1 allergen. In this study, we analyzed the Ab (IgE, IgG subclass, IgA, IgM) response to Bet v 1, recombinant and synthetic Bet v 1-derived peptides in birch pollen allergic patients who had been vaccinated with the derivatives or adjuvant alone. Furthermore, we studied the induction of IgE-mediated skin responses in these patients using Bet v 1 and Bet v 1 fragments. Both types of vaccines induced a comparable IgG1 and IgG4 response against new sequential epitopes which overlap with the conformational IgE epitopes of Bet v 1. This response was 4- to 5-fold higher than that induced by immunotherapy with birch pollen extract. Trimer more than fragments induced also IgE responses against new epitopes and a transient increase in skin sensitivity to the fragments at the beginning of therapy. However, skin reactions to Bet v 1 tended to decrease one year after treatment in both actively treated groups. We demonstrate that vaccination with folded and unfolded recombinant allergen derivatives induces IgG Abs against new epitopes. These data may be important for the development of therapeutic as well as prophylactic vaccines based on recombinant allergens.     

Oral Immunotherapy for Pollen Allergy Using T-Cell Epitope-Containing Egg White Derived from Genetically Manipulated Chickens

Peptide immunotherapy using T-cell epitopes is expected to be an effective treatment for allergic diseases such as Japanese cedar (Cryptomeria japonica; Cj) pollinosis. To develop a treatment for pollen allergy by inducing oral tolerance, we generated genetically manipulated (GM) chickens by retroviral gene transduction, to produce a fusion protein of chicken egg white lysozyme and a peptide derived from seven dominant human T-cell epitopes of Japanese cedar pollen allergens (cLys-7crp). The transgene sequence was detected in all chickens transduced with the retroviral vector. Transduction efficiency in blood cells correlated to transgene expression. Western blot analysis revealed that cLys-7crp was expressed in the egg white of GM hens. Mice induced to develop allergic rhinitis by Cj pollinosis were fed with cLys-7crp-containing egg white produced by GM chickens. Total and Cj allergen (Cry j 1)-specific IgE levels were significantly decreased in allergic mice fed with cLys-7crp-containing egg white compared with allergic mice fed with normal egg white. These results suggest that oral administration of T-cell epitope-containing egg white derived from GM chickens is effective for the induction of immune tolerance as an allergy therapy.