Cloning and IgE binding of a recombinant allergen from the mite Blomia tropicalis, homologous with fatty acid-binding proteins.
To characterize the allergens of Blomia tropicalis, a cDNA library was constructed and screened with allergic sera from asthmatic patients. One clone, Bt6, was subcloned and sequenced. The nucleotide sequence of 934 bp length shows a 390-bp reading frame which encodes a 130-amino acid protein with a MW 14.8 kD. No potential glycosylation site was found in the predicted protein. The inferred amino acid sequence has no homology to known allergens. It has a cytosolic fatty acid-binding protein (FABP) signature at 5-22 amino acid residues, 42.3% identity with the Sm14-FABP of Schistosoma mansoni and 36% identity with FABPs from rat, mouse, bovine and human. The protein was expressed as a GST fusion protein and the purified GST-Bt6 used for dot blot, RAST and RAST inhibition assays. The frequency of IgE binding of allergic sera to Bt6 was low (11%) and usually weak. One positive serum did, however, show strong reactivity by RAST and dot blot and Bt6 could inhibit 60% of the IgE binding of this serum to the B. tropicalis extract. These data show that Bt6 encodes a mite FABP with allergenic properties, which are pronounced in some atopic subjects.
Caraballo
L
L
University of Cartagena, Columbia.
Puerta
L
L
Jimenez
S
S
Martinez
B
B
Mercado
D
D
Avjiouglu
A
A
Marsh
D
D
D000485:Allergens / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D052179:Antigens, Plant; D001483:Base Sequence; D001666:Binding Sites, Antibody; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D003001:Cloning, Molecular; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids / Q000378:metabolism; D005982:Glutathione Transferase / Q000235:genetics; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000378:metabolism*; D008925:Mites / Q000276:immunology*; D008969:Molecular Sequence Data; D018996:Myelin P2 Protein / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D011852:Radioallergosorbent Test; D011994:Recombinant Proteins / Q000276:immunology* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013917:Thrombin; D025521:Tumor Suppressor Proteins
D000485:Allergens; D052179:Antigens, Plant; D002352:Carrier Proteins; C107608:FABP7 protein, human; C490174:Fabp7 protein, rat; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids; D018996:Myelin P2 Protein; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D011994:Recombinant Proteins; D025521:Tumor Suppressor Proteins; C105335:allergen Bt6, Blomia tropicalis; D007073:Immunoglobulin E; D005982:Glutathione Transferase; D013917:Thrombin