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Summary Background Almost 100 million allergic patients are sensitized to the major birch pollen allergen, Bet v 1, a 17 kDa protein containing most of the IgE epitopes present in pollens of trees belonging to the Fagales order and plant-derived food. Objective Our aim was to develop an approach for the rational design of B cell epitope-derived, non-allergenic peptide allergy vaccines. Methods According to the three-dimensional (3-D) structure of birch pollen allergen, Bet v 1, six peptides comprising 25–32 preferably solvent-exposed amino acids were synthesized. Results Because of lack of secondary structure, the peptides showed no allergenic activity in allergic patients. In a mouse model of birch pollen allergy, peptide vaccination induced Bet v 1-specific IgG and prevented IgE-mediated allergic sensitization to Bet v 1. The protective role of peptide-induced blocking antibodies is demonstrated by inhibition of allergic patients IgE binding to the allergen and by blocking of allergen-induced basophil degranulation. Conclusion Our results indicate the mechanistic importance of blocking antibodies for allergy vaccination and present a B cell epitope-based approach for the rational design of safe peptide allergy vaccines whenever the structure of the disease-eliciting allergen is known.

Summary Background We have recently engineered recombinant derivatives of the major birch pollen allergen Bet v 1 (rBet v 1 fragments and trimer) with strongly reduced allergenic activity. Objective The aim of this study was the in vivo characterization of potential allergy vaccines based on Al(OH)3-adsorbed genetically modified rBet v 1 derivatives in mice. Methods BALB/c mice were immunized either with courses of nine injections of increasing doses of Al(OH)3-adsorbed rBet v 1 wild-type, rBet v 1 fragments, rBet v 1 trimer or Al(OH)3 alone in weekly intervals or with three high-dose injections applied in intervals of 3 weeks. Humoral immune responses to rBet v 1 wild-type and homologous plant allergens were measured by ELISA and Western blotting, and the ability of mouse antibodies to inhibit the binding of allergic patients IgE to Bet v 1 was studied by ELISA competition experiments. Results In both schemes, hypoallergenic rBet v 1 derivatives induced low IgE but high IgG1 responses against rBet v 1 wild-type. The IgG1 antibodies induced by genetically modified rBet v 1 derivatives cross-reacted with natural Bet v 1 and its homologues from alder (Aln g 1) as well as hazel (Cor a 1) and strongly inhibited the binding of birch pollen allergic patients' IgE to Bet v 1 wild-type. Conclusion Genetically modified hypoallergenic rBet v 1 derivatives induce blocking antibodies in vivo. Their safety and efficacy for the treatment of birch pollen and associated plant allergies can now be evaluated in clinical immunotherapy studies.

In a BALB/c mouse model, we have previously identified a ras oncogene peptide that contained both CD8 + and CD4 + T cell epitopes in a nested configuration. In this study, we developed several plasmid DNA minigene vectors encoding these determinants and examined whether they could induce antigen (Ag)-specific CD8 + cytotoxic and CD4 + lymphoproliferative responses. Furthermore, we compared two different immunization procedures, epidermal gene gun inoculation and intradermal (i.d.) injection of saline plasmid DNA, along with several approaches addressing different aspects of immune modulation. We demonstrated that each DNA plasmid induced the relevant Ag-specific cellular immune response. Gene gun inoculation was superior to that of needle injection for induction of the CTL response. Moreover, DNA plasmids containing both ras epitopes induced the highest CTL response, as compared with vector preparations containing only the CD8 + epitope. These results suggested that a DNA plasmid expressing nested mutant ras epitope-specific CD4 + and CD8 + T cell epitopes can be processed in vivo to induce both subset-specific T cell responses, and that the addition of the helper epitope quantitatively improved the development of the CTL response, which may have implications for DNA-based anti-tumor immunotherapies.

In atopic patients, programming towards a preferential Th2 immunity leads to IgE antibody production and cellular Th2 immunity against otherwise harmless antigens. We report the development of prophylactic and therapeutic DNA vaccines for the major birch-pollen allergen, Bet v 1. We constructed three DNA vaccines, coding for the complete cDNA, coding for two hypoallergenic fragments or coding for a hypoallergenic Bet v 1 mutant. The protective effect was studied in mice pretreated by intradermal DNA injections, then sensitized with Bet v 1 protein. Mice pretreated with any of the three Bet v 1-specific DNA vaccines were protected against allergic sensitization to Bet v 1. Protection was characterized by a lack of Bet v 1-specific IgE production, a lack of basophil activation and an enhanced IFN-gamma expression. DNA vaccines with wild-type Bet v 1 induced strong Bet v 1-specific antibody responses whereas DNA vaccines with hypoallergenic Bet v 1 derivatives induced no (fragments) or only transient (mutant) Bet v 1-specific antibody responses. A therapeutic approach with the fragment-DNA vaccine reduced IgE production and stimulated a sustained Th1 cytokine milieu. Our results demonstrate that DNA vaccines with hypoallergenic forms of the allergen specifically protect against sensitization and suppress established Th2-type responses. This concept may be applied for the development of safe and specific DNA vaccines for the prophylaxis and therapy of allergic diseases.

Nuclear retinoid receptors - retinoic acid inducible transcription factors - participate in pathways influencing many components of the immune system. In the present study in vivo effects of DNA-based immunization of mice on binding parameters of all-trans retinoic acid receptors (RARs) in spleen cell nuclei was investigated. A eucaryotic expression vector encoding the gene for the model enzyme beta-galactosidase of Escherichia coli (pCMV-beta) was used for intradermal injection. Furthermore, immunostimulatory CpG motifs, which stimulate the expression of various cytokines and may serve as a 'danger signal' for the mammalian immune system, were coinjected as oligodeoxynucleotides. The results demonstrate that the concentration of RARs was significantly reduced in the late phase of the primary immune response (21 days after injection of plasmid DNA-indicated by high affinity IgG antibodies and IFN-gamma expression). Coinjection of CpG motifs did not change the course of the humoral response but enhanced and accelerated the proliferative response and expression of IFN-gamma, which correlated with the reduced RARs concentration.

Background Allergy vaccines based on natural allergen extracts contain greatly varying amounts of individual allergens with different immunogenicity. Objective To develop a novel type of allergy vaccine for complex allergen sources that combines defined amounts of the major allergens in the form of single hybrid molecules. Methods A hybrid molecule was engineered by PCR-based mending and expression of the cDNAs coding for the 4 major grass pollen allergens and compared with its single components by circular dichroism analysis, T-cell proliferation, ELISA competition, and histamine release assays. Immune responses to the hybrid molecule were studied in BALB/c mice and rat basophil leukemia assays. Results The hybrid contained most of the B-cell epitopes of grass pollen and could be used to diagnose allergy in 98% (n=652) of patients allergic to grass pollen. Immunization of mice and rabbits with the hybrid induced stronger and earlier IgG antibody responses than equimolar mixtures of the components, which can be explained by the induction of stronger T-cell responses by the hybrid versus the individual components. IgG antibodies induced by vaccination with the hybrid blocked immediate allergic reactions, as demonstrated by rat basophil degranulation assays in a murine model of grass pollen allergy. Conclusion We demonstrate for grass pollen allergy that recombinant hybrid molecules covering the spectrum of the disease-eliciting epitopes of complex allergen sources can be engineered.

Background: As the major allergen of mugwort pollen, Art v 1 is an important target for specific immunotherapy. However, both recombinant protein as well as a gene vaccine for Art v 1 failed to be immunogenic in mice. In order to improve immunogenicity we focused on genetic immunization because interspecific differences of codon usage have been shown as an obstacle for effective induction of immune responses with gene vaccines encoding infectious pathogens. Objective: In order to find out, whether codon usage might also be used to improve genetic immunization with allergen genes, the response against a gene vaccine expressing the wild-type gene of Art v 1 (pCMV-wtArt) was compared with a synthetic codon-optimized vector with human codon usage (pCMV-humArt). Methods: Balb/c mice were injected intradermally with pCMV-wtArt or pCMV-humArt. In vitro expression levels of both constructs were compared in transfection experiments. Total immunoglobulin G (IgG), IgG1, IgG2a and IgE antibodies were analyzed by enzyme-linked immunosorbent assay and the anaphylactic activity of the sera was determined by allergen-specific degranulation of rat basophil leukemia-2H3 cells. Results: No immune response was detectable with the gene vaccine expressing the wildtype Art v 1, but immunization with pCMV-humArt revealed a strong and allergen-specific induction of antibody responses. The antibodies recognized both the recombinant as well as the purified natural (glycosylated) Art v 1 molecule. The response type was Th1-biased, as indicated by high levels of IgG2a antibodies. Expression analysis with B16 mouse melanoma cells transfected with pCMV-humArt or pCMV-wtArt revealed an impaired expression of the wild-type vector but normal translation after recoding. Conclusion: The results demonstrate that optimization of codon usage offers a simple way to improve immunogenicity and therefore should be routinely considered in the development of gene vaccines for the treatment of allergy.

In the past 10 years, a great number of studies have demonstrated that injection of plasmid DNA coding for certain genes results in the induction of humoral and cellular immune responses against the respective gene product. This vaccination approach covers a broad range of possible applications, including the induction of protective immunity against viral, bacterial, and parasitic infections, and it opens new perspectives for treatment of cancer. Surprisingly, DNA immunization also turned out as a promising novel type of immunotherapy against allergy. In this paper, we describe the construction of DNA vaccines for application in allergy models. Beyond, we offer a palette of recently developed modulations to optimize DNA vaccines for allergy treatment by increasing their immunogenicity and minimizing their anaphylactic potential.

The present study outlines the characterization of a DNA-based immune response against the OspC antigen, one of the most promising candidates for a Borrelia vaccine. Balb/c mice were injected intradermally with plasmid DNA encoding the OspC gene (lacking the natural leader sequence) under transcriptional control of the cytomegalovirus (CMV) promotor. Immunization with this construct elicited only a marginal response, which was drastically improved by a fusion construct containing the human tissue plasminogen activator (hTPA) signal sequence. The results indicate that for DNA-based immunization against OspC an ER-targeting signal may be necessary for both antibody production as well as cellular immune responses.

Inflammatory cytokines in vitro are believed to be involved in the regulation of type I iodothyronine 5'-deiodinase (5'-DI) activity. The present study was undertaken to investigate in vivo effects of DNA immunization of mice on the 5'-DI activity in the liver. A mammalian expression vector encoding the beta-galactosidase (pCMV-betagal) was used for intradermal immunization. Furthermore, immunostimulatory CpG motifs, which induce the expression of IL-6, IL-12, IL-18, TNF-alpha/beta and IFN-gamma were coinjected as oligodeoxynucleotides. From our data we conclude that the activity of 5'-DI in mouse liver when compared to non-immunized animals (100%) was found to be significantly enhanced by DNA immunization 2 weeks (175.7%) or 3 weeks (192.6%) after the plasmid injection. In addition, the activity of the 5'-DI in mouse liver was markedly enhanced 2 weeks (252.4%) or 3 weeks (243.3%) after the injection when CpG motifs were applied together with the plasmid DNA.

The investigation of cellular interactions during the regeneration of splenic transplants depends upon distinguishing host cells from graft derived cells. As a cell marker which, in contrast to many other marker systems, does not affect histocompatibility, the non-expressed transgene mMT-HGHRH-1 was introduced by mating into NMRI inbred mice to generate the transgenic mouse line BSM. By transplanting non-transgenic NMRI splenic tissue into transgenic BSM hosts, host derived cells could be identified in the transplants by in situ hybridization after regeneration. In a reciprocal approach, implant derived cells were detected in a transgenic trasplant after 3 weeks of regeneration in a non-transgenic host. Relative amounts of transgenic cells in transplant cross-sections were estimated from the signal intensity of autoradiographs by densitometry and computer analysis. This approach could be broadly applied in studies of transplantation systems.

The use of nitrocellulose paper as a solid phase matrix for protein immobilization and its application in immunoaffinity chromatography is described. Pieces of nitrocellulose paper were frozen in liquid nitrogen and ground to a powder (NCP) which was then fractionated according to particle size by repeated sedimentation/resuspension cycles in water. The flow properties of different NCP fractions were compared with those of Sephadex G-50. Protein binding capacity and binding dynamics were investigated in a model system with bovine serum albumin (BSA) in phosphate buffered saline. Applications of the material are illustrated by batch chromatography for the removal of anti-carrier protein antibodies from a hapten antiserum and by affinity purification of a hapten-specific antibody fraction using NaSCN elution from haptenated NCP. Furthermore, the applicability of the material in column chromatography is demonstrated by elution of a monospecific fraction of anti-fluorescein antibodies from a hapten/carrier mixed bed column by excess of soluble hapten. The results demonstrate that NCP chromatography appears to be a cheap and useful alternative to many other chromatographic media used for protein immobilization.

Polyspecific antisera against antigen mixtures are important tools for many experimental purposes. However, following immunization with extracts containing a great number of different proteins, many antigens remain non-immunogenic. Therefore, the improvement of the antibody spectrum of antisera is an essential goal in maximising the power and applicability of many serological analyses. In the present report we demonstrate that the additional use of heterologous (i.e., antigenically related, but not identical) antigen mixtures for immunization increases the variety of antibodies in polyspecific antisera as well as the antibody titer against weak immunogens.

The method described in the present paper permits the detection of antigenically related proteins within or between different antigen mixtures. For this purpose two separate SDS-polyacrylamide gels are run (the antigen mixture is applied to the entire width of the gel) and each gel is blotted on to a separate nitrocellulose paper. One sheet ('donor sheet') is incubated with antiserum and placed on to the other blot ('receptor sheet') so that the antigen bands are perpendicular to each other. Subsequently the antibodies from the donor sheet are blotted on to the receptor sheet in alkaline borate buffer containing 1 M NaSCN, which dissociates antigen-antibody complexes. After the removal of the donor sheet the receptor sheet containing the transblotted antibodies is equilibrated in phosphate-buffered saline in order to reconstitute the binding conditions. Antibodies which have bound to receptor antigens during this equilibration period are detected by the use of a peroxidase labelled 2nd antibody. Because each band on the donor sheet crosses each band on the receptor sheet during the transfer, the antibodies from each band of the donor sheet are able to react with each antigen band of the receptor sheet. The validity of the method was established by demonstrating the crossreactivity of a polyclonal antiserum against the intact bovine gamma globulin molecule with the heavy and light chain subunits (and partial reduction products of the molecule) and the absence of crossreactivity between heavy and light chains. In a second experiment crossreacting antigens of different molecular weight were detected within several strains of Escherichia coli. In addition, comparisons of different strains of Escherichia coli revealed crossreacting antigens of identical as well as of different molecular weight.

Rationale Cladosporium herbarum ( C. herbarum ) is one of the most important and world wide occurring allergenic fungal species. Sensitization to C. herbarum (and fungi in general) has often been associated with asthma, chronic idiopathic urticaria, and allergic dermatitis. It is therefore interesting to define the allergen repertoire of C. herbarum . We have undertaken here to characterize a new Cladosporium allergen, which was isolated from a cDNA library of C. herbarum spores and mycelia and to compare it with its human homologue. Methods A C. herbarum cDNA library constructed in the lambda-ZAP vector was screened with sera of patients allergic to Cladosporium . The newly isolated cDNA clone and its human homolog were expressed in E. coli , purified to homogeneity and immunologically analyzed by IgE blots. Results The characterized allergen is a close homolog of the human histamine releasing factor (TCTP). IgE antibodies of three of five patients, which recognize the Cladosporium allergen, also recognize the human protein in immune blots. Conclusion The new allergen will not only contribute to define more comprehensively the allergen repertoire of C. herbarum , it also allows us to test the role of a new auto-antigen with a possible role in certain severe forms of allergic disease.

Rationale Art v 1 is the major mugwort (Artemisia vulgaris) pollen allergen and therefore represents one of the main causes of late summer pollinosis in Europe. Cross-reacting specific IgE antibodies can lead to clinically significant reactions with other members of the Compositae plant family (e.g. ragweed) in other geographic areas, such as Northern America. Furthermore, previous studies revealed cross-reactivity between mugwort pollen and certain food, known as the "celery-mugwort-spice-syndrome". Methods In vitro cross-reactivity between Art v 1 and proteins from other Compositae-, grass- and tree pollen and common food allergen sources was investigated by immunoblot and IgE-inhibition experiments using the following antibodies: polyclonal rabbit anti-natural Art v 1, rabbit anti-recombinant Art v 1, moAb anti-Art v 1, produced by genetic immunization, and sera from mugwort and ragweed sensitized patients. Results The glycoallergen Art v 1 shares epitopes with proteins originating mainly from the botanically related plants of the Compositae family (Artemisia absinthium, Ambrosia artemisifolia, Ambrosia psilostachya, Ambrosia trifida and Helianthus annuus) and with the timothy grass (Phleum pratense) major allergen Phl p 1. We could not observe cross-reactivity between Art v 1 and proteins in extracts from tree pollen (Betula verrucosa) and food (apple and celery). Conclusions The Art v 1 cross-reactive epitopes seem to encompass both the Art v 1 polypeptide and O-glycans attached to its C-terminal domain. Cross-reactivity with the glycoprotein Phl p 1 seems to be due to structural similarities in the Art v 1 defensin like domain or to sugar chains linked to its proline rich domain.

Objective To examine the sequence polymorphism of Art v 1, the major allergen of mugwort pollen. Methods After screening of a mugwort pollen lambda ZAP II cDNA library with antibodies and DNA probes, forty cDNA clones coding for Art v 1 were isolated and sequenced. For the expression in competent E.coli strain BL 21 (+RIL), the cDNAs without the natural leader sequence were cloned into the expression plasmid pHis2. The immunoreactivity of purified Histagged recombinant isoforms was tested by immunoblots with a polyclonal rabbit serum raised against rArt v 1, a moAb anti-Art v 1 produced by genetic immunization and sera from 16 subjects allergic to mugwort pollen. Results The derived protein sequences of 7 different isoforms (corresponding to 25 different cDNAs) showed amino acid sequence identities ranging from 94% (6 amino acids exchanges) to 99% (a single amino acid exchange). Interestingly, all amino acid exchanges in the isoforms were restricted to the C-terminal hydroxyproline-rich domain, which carries the O-glycans of Art v 1. The mature isoforms were expressed in E.coli at a concentration of approximately 1 mg/L culture, depending on the isoform. All seven recombinant Art v 1 isoforms displayed similar IgG- and IgE-binding capacity. Conclusion Production of glycosylated recombinant isoforms in a plant-based expression system will help to clarify if the amino acid exchanges result in differences of the glycosylation pattern and antibody binding properties of Art v 1.

The grass pollen allergen, Phl p 7, belongs to a family of highly cross-reactive calcium-binding pollen allergens. Because Phl p 7 contains most of the disease-eliciting epitopes of pollen-derived calcium-binding allergens, hypoallergenic variants were engineered according to the x-ray crystal structure of Phl p 7 for allergy vaccination. In three recombinant variants, amino acids essential for calcium binding were mutated, and two peptides comprising the N- and C-terminal half were obtained by synthetic peptide chemistry. As determined by circular dichroism analysis and size exclusion chromatography coupled to mass spectrometry, recombinant mutants showed altered structural fold and lacked calcium-binding capacity, whereas the two synthetic peptides had completely lost their structural fold. Allergic patients’ IgE Ab binding was strongest reduced to the variant containing two mutations in each of the two calcium-binding sites and to the peptides. Basophil histamine release and skin test experiments in allergic patients identified the peptides as the vaccine candidates with lowest allergenic activity. Immunization of rabbits with the peptides induced IgG Abs that blocked allergic patients’ IgE binding to Phl p 7 and inhibited allergen-induced basophil degranulation. Our results indicate that disruption of an allergen’s three-dimensional structure represents a general strategy for the generation of hypoallergenic allergy vaccines, and demonstrate the importance of allergen-specific IgG Abs for the inhibition of immediate allergic symptoms.