Cloning, Expression, and Characterization of Der f 7, an Allergen of Dermatophagoides farinae from China

• Published in: Journal of medical entomology Vol. 47; no. 5; pp. 868 - 876
• Main Authors: Cui, Yu-Bao, Cai, Hong-Xing, Zhou, Ying, Gao, Cui-Xiang, Shi, Wei-Hong, Yu, Ming, Li, Li
• Format: Journal Article
• Language: English
• Published: England 01.09.2010
• Subjects: allergens; Amino Acid Sequence; amino acid sequences; Animals; Antigens, Dermatophagoides - genetics; Antigens, Dermatophagoides - metabolism; Arthropod Proteins; Base Sequence; China; Cloning, Molecular; Dermatophagoides farinae; Dermatophagoides farinae - immunology; Dermatophagoides farinae - metabolism; gene expression; Gene Expression Regulation - genetics; Gene Expression Regulation - physiology; molecular cloning; Molecular Sequence Data; Phylogeny; polymerase chain reaction; China
• ISSN: 0022-2585; 1938-2928
• DOI: 10.1603/ME09180

A full-length cDNA encoding house dust mite allergen Der f 7 from Dermatophagoides farina. (Acari: Pyroglyphidae) from China was cloned, sequenced, and successfully expressed. A reference sequence (GenBank accession AY283292) was used to design polymerase chain reaction primers. Analysis revealed eight mismatched nucleotides in five Der f 7 cDNA clones, and the projected amino acid sequence contained six incompatible residues. These results suggest that the sequence of Der f 7 may be polymorphic. Further bioinformatic analysis revealed that the mature Der f 7 allergen had a molecular mass of ≈21.88 kDa and a theoretical isoelectric point of 4.90. Der f 7 protein secondary structure was composed of α helix (56.63%), extended strand (5.10%), and random coil (38.27%). Group 7 allergens are present in Pyroglyphidae, Acaridae, and Glycyphagidae families, and homology analysis revealed a 86% similarity between Der f 7 and Der p 7. Furthermore, a phylogenetic tree constructed of group 7 allergens from different mite species revealed that Der f 7 and Der p 7 clustered with 100% bootstrap support. Bioinformatics-driven characterization of Der f 7 allergen as conducted in this study may contribute to diagnostic and therapeutic applications for dust mite allergies.