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Protein sequence analysis and mapping of IgE and IgG epitopes of an allergenic 98-kDa Dermatophagoides farinae paramyosin, Der f 11


Kaw-Yan Chua, Department of Pediatrics
Faculty of Medicine
National University of Singapore
Lower Kent Ridge Road
Singapore 119074


Background: A 98-kDa mite paramyosin (Der f 11) from Dermatophagoides farinae (Df) is highly allergenic, and its cDNA (Df642) has been cloned. This paper describes the sequence characteristics and the mapping of the immunodominant human IgE and IgG epitopes of Der f 11.

Methods: The protein sequence analysis was performed with a combination of FASTA, GCG, and CLUSTAL W computing packages. The whole cDNA insert and its PCR-derived DNA fragments were generated and expressed in E. coli. These overlapping recombinant peptides (F1 to F5) were used for B-cell epitope mapping with 18 mite-allergic sera by dot immunoassays.

Results: Df642 cDNA encodes a partial sequence that contains the 2nd to 26th 28-residue repeats and lacks the N-terminus and the C-terminus. The sequence identity of the Der f 11 with other known paramyosins is 34–60%. The dominant IgE epitopes are located in peptides F1 and F4, whereas the dominant IgG epitopes are located in peptides F1 and F2. These peptides are more reactive than whole rDf642.

Conclusions: Mite paramyosin is very similar to other known paramyosins. The human IgE and IgG epitopes are scattered throughout the entire molecule. Data also indicate the presence of unique IgE and IgG epitopes in Der f 11.