Bla g 6: A troponin C allergen from Blattella germanica with IgE binding calcium dependence - 20/08/11
Reprint requests: Anna Pomés, PhD, INDOOR Biotechnologies, Inc, 1216 Harris Street, Charlottesville, VA 22903.Cardiff, United Kingdom, Charlottesville, Va, and Singapore
Abstract |
Background |
The known cockroach allergens do not appear to account for the full repertoire of IgE responses.
Objective |
To identify and investigate the importance of other Blattella germanica allergens contributing to cockroach allergy.
Methods |
A B germanica cDNA library was screened with pooled sera from patients with cockroach allergy. Three isoallergens of troponin C (Bla g 6) were cloned and expressed in Pichia pastoris. Homology modeling was performed by using Swiss-Model. IgE responses to purified allergens were simultaneously measured in 104 sera by using a fluorescent multiplex array system. The effect of calcium on IgE binding was investigated by ELISA.
Results |
Three isoallergens, Bla g 6.0101, Bla g 6.0201, and Bla g 6.0301, were identified which share homology with insect troponin Cs and vertebrate calmodulins (61% to 78% and 42% to 44% amino acid identity, respectively) and have 2 EF-hand calcium binding domains. Molecular models of Bla g 6 showed 2 structurally homologous lobes connected by a linker that confers flexibility to the allergen. The prevalence of IgE binding to recombinant Bla g 6 was 14%. Calcium depletion by 10 mmol/L ethyleneglycol-bis-(β-aminoethylether)-N,N,N′,N′-tetraacetic acid did not significantly affect IgE binding in most cases. Interestingly, addition of 10 mmol/L CaCl2 after calcium depletion increased IgE binding by approximately 2-fold, a finding not previously reported for calcium binding allergens.
Conclusion |
Bla g 6 is a troponin allergen with a calcium dependent IgE reactivity that may be involved in muscle contraction.
Clinical implications |
Bla g 6 homologous allergens may occur among other insects and cause cosensitization or allergenic cross-reactivity.
Le texte complet de cet article est disponible en PDF.Key words : Asthma, allergy, allergens, cockroach, calcium binding proteins, multiplex array technology
Abbreviations used : EGTA, r
Plan
| The names Bla g 6.0101, Bla g 6.0201, Bla g 6 0.301, and Per a 6 were accepted by the World Health Organization/International Union of Immunological Societies Subcommittee of Allergen Nomenclature. The GenBank accession numbers for the nucleotide sequence encoding for these allergens are DQ279092, DQ279093, DQ279094, and AY792950, respectively. Presented at the American Academy of Allergy, Asthma, and Immunology Annual Meeting, Miami, Fla, March 2006. Supported by INDOOR Biotechnologies, Inc. Disclosure of potential conflict of interest: A. Pomés, J. Hindley, and S. Wünschmann are employed by INDOOR Biotechnologies. M. Chapman is the owner and is employed by INDOOR Biotechnologies, has patent licensing arrangements with Heska Corp, and has received grants from the National Institute of Environmental Health Sciences. F. T. Chew has received research grants from the Singapore Biomedical Research Council (BMRC), Singapore National Medical Research Council (NMRC), and the National University of Singapore Academic Research Fund (ARF). The rest of the authors have declared that they have no conflict of interest. |
Vol 117 - N° 6
P. 1389-1395 - juin 2006 Retour au numéro
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