RESUMO
BACKGROUND: The aim of this work was to understand the molecular features that trigger the cross-reactivity observed between Der p 5 from Dermatophagoides pteronyssinus, Blo t 5 from Blomia tropicalis, and Der f 5 from D. farinae. METHODS: We collected serum from 60 house dust mite (HDM)-allergic patients residing in the Dellys area of Boumerdès province in northern Algeria. The presence of specific IgE to Der p 5, Der f 5, and Blo t 5 was analyzed. We performed in silico analysis of the structure of the different allergens in order to identify epitopes that can elicit the cross-reactivity of the sera. Synthetic peptides corresponding to the linear epitope sequence of Der p 5, Der f 5, and Blo t 5 were used to evaluate its implication in the cross-reactivity between the allergens. We also modified the sequence of the conformational epitope of Der p 5 by site-directed mutagenesis to mimic Blo t 5. RESULTS: Several sera of patients allergic to HDM contained specific IgE antibodies to Der p 5 and Blo t 5. We demonstrated that the linear epitope of Der p 5 and Blo t 5 is not involved in the cross-reactivity of the sera. Furthermore, mutations introduced in the sequence of Der p 5 to mimic Blo t 5 could not modulate the cross-reactivity between them. CONCLUSIONS: The major linear IgE epitopes of Der p 5 and Blo t 5 are involved in species-specific recognition. Our results may be useful for the development of a hypoallergenic vaccine against HDM group 5 allergens.
Assuntos
Alérgenos/imunologia , Antígenos de Dermatophagoides/imunologia , Proteínas de Artrópodes/imunologia , Reações Cruzadas/imunologia , Dermatophagoides pteronyssinus/imunologia , Epitopos/imunologia , Imunoglobulina E/imunologia , Adulto , Alérgenos/genética , Animais , Especificidade de Anticorpos , Antígenos de Dermatophagoides/genética , Proteínas de Artrópodes/genética , Dermatophagoides pteronyssinus/genética , Ensaio de Imunoadsorção Enzimática , Mapeamento de Epitopos , Epitopos/química , Epitopos/genética , Feminino , Humanos , Hipersensibilidade/sangue , Hipersensibilidade/diagnóstico , Hipersensibilidade/imunologia , Imunoglobulina E/sangue , Masculino , Pessoa de Meia-Idade , Mutagênese , Proteínas Recombinantes , Adulto JovemRESUMO
BACKGROUND: Der p 5 is an important allergen of Dermatophagoides pteronyssinus that plays a key role in allergic airway diseases. Its three dimensional structure (PDB 3MQ1) consists of three anti-parallel α-helices arranged in a helical bundle. Aggregation of Der p5 can modulate its allergenicity. This study aimed to identify the key residues of IgE binding epitopes of Der p 5. METHODS: IgE binding epitopes of Der p 5 were characterized as follow. An in silico prediction of the epitope was performed with the help of SEPPA program. We also made a mapping of the epitope by using an overlapping library of peptides that encompass the sequence of mature Der p 5. Finally, an alanine scanning mutagenesis allowed us to define the key residues of the allergen involved in its interaction with IgE. The integrity of the structure of the different protein's mutants was assessed by far UV circular dichroism. RESULTS: The presented data indicate that the major epitope sequence of Der p 5 is 90DRLMQRKDLDIFEQYNLEM108. Residues L98, D99, I100, F101, E102 and Y104 appear to be important for IgE binding. CONCLUSION: This study highlighted the residues of Der p 5 essential for IgE binding. The identification of the major residues epitope of Der p 5 allergen may participate in the selection and engineering of new hypoallergens used in immunotherapy.