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RESEARCH PRODUCT

A Hybrid Expressing Genetically Engineered Major Allergens of the <i>Parietaria</i> Pollen as a Tool for Specific Allergy Vaccination

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<i>Background:</i> Allergy is an immunological disorder affecting about 25% of the population living in the industrialized countries. Specific immunotherapy is the only treatment with a long-lasting relief of allergic symptoms and able to reduce the risk of developing new allergic sensitizations and inhibiting the development of clinical asthma in children treated for allergic rhinitis. <i>Methods:</i> By means of DNA recombinant technology, we were able to design a head to tail dimer expressing disulphide bond variants of the major allergen of the <i>Parietaria </i>pollen. IgE binding activity was studied by Western blot, ELISA inhibition assays and the skin prick test. T cell recognition was studied by peripheral blood mononuclear cell proliferation. The immunogenicity of the hybrid was studied in a mouse model of sensitization. <i>Results:</i> In vitro and in vivo analysis showed that the disruption of specific cysteine residues in both allergens caused a strong reduction in IgE binding activity of the PjEDcys hybrid. In addition,we were able to show that a reduction in the IgE epitope content profoundly reduced the anaphylactic activity of the hybrid (from 100 to 1,000 times less than wild-type allergens) without interfering with the T cell recognition. Sera from BALB/c mice immunized with the hybrid were able to bind the natural <i>Parietaria</i> allergens and to inhibit the binding of human IgE to wild-type Par j 1 and Par j 2 allergens up to 90%. <i>Conclusion:</i> Our results demonstrate that hybrid-expressing disulphide bond variants of the major allergens of the <i>Parietaria</i> pollen displayed reduced allergenicity and maintained T cell reactivity for induction of protective antibodies.