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Lack of human IgE cross‐reactivity between mite allergens Blo t 1 and Der p 1
Author(s) -
Cheong N.,
Soon S. C.,
Ramos J. D. A.,
Kuo I. C.,
Kolortkar P. R.,
Lee B. W.,
Chua K. Y.
Publication year - 2003
Publication title -
allergy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.363
H-Index - 173
eISSN - 1398-9995
pISSN - 0105-4538
DOI - 10.1034/j.1398-9995.2003.00215.x
Subject(s) - mite , complementary dna , immunoglobulin e , house dust mite , recombinant dna , biology , microbiology and biotechnology , peptide sequence , pichia pastoris , antibody , immunology , gene , biochemistry , botany
Background: The group 1 mite allergens are the most significant indoor allergens and they belong to the papain‐like cysteine protease family. To date there is only one published report on the isolation and characterization of group 1 allergens from Blomia tropicalis mites. The aims of the study are to determine the cross‐reactivity between group 1 allergens and to evaluate their clinical importance in allergic patients. Methods: The full‐length Blo t 1 gene was obtained by SMART TM RACE cDNA amplification method using gene‐specific primers. The sequence alignment was performed using LOOK followed by three‐dimensional homology modeling. The cDNA was expressed in Pichia pastoris as a secretory protein. Identification of native Blo t 1 in crude mite and spent mite medium extracts was done by Western immunoblot using monoclonal antibody. Allergenicity of recombinant Blo t 1 and native Der p 1 was examined by human IgE ELISA with 80 asthmatic sera. Results: The cDNA sequence consists of 1105 base pairs, including 5′‐ and3′‐untranslating regions, encoding an open reading frame of 330 amino acid residues. The predicted molecular weight of the deduced protein was approximately 38 kDa. Blo t 1 shared 53 and 34% nucleotide and amino acid, respectively, sequence homology with Der p 1. Native Blo t 1 was detected in both crude mite and spent mite medium extracts, and its estimated molecular weight was about 26 kDa. The recombinant Blo t 1 reacted positively with IgE in 90 and 65% of sera from asthmatic children and adults, respectively, indicating that it is a major allergen. The correlation of human IgE reactivity between Blo t 1 and Der p 1 was low in these sera. Conclusion: The full‐length cDNA encoding group 1 Blomia tropicalis mite allergen (designated as Blo t 1) has been characterized and expressed from local mites in Singapore. This fecal allergen showed high frequency of human IgE reactivity with asthmatic sera in the tropics and there was a low correlation of IgE reactivity between Blo t 1 and Der p 1.