title: Group 1 Allergen Genes in Two Species of House Dust Mites, Dermatophagoides farinae and D. pteronyssinus (Acari: Pyroglyphidae): Direct Sequencing, Characterization and Polymorphism.
abstract: Group 1 allergens of Dermatophagoides farinae (Der f 1) and D. pteronyssinus (Der p 1) dominate overall allergic responses in house dust mite allergy patients. The need for accurate identification and characterization of representative variants of group 1 allergens in any given geographic locality has been emphasized for development of appropriate allergen extracts. Regional amino acid sequence polymorphism has been described but the extent of this polymorphism is not well understood. Such data are completely absent for the USA and many other countries. Most previous studies used cDNA libraries generated by reverse transcriptase (RT-PCR) and/or primers amplifying shorter fragments of this gene. Using novel species-specific primers and direct PCR, we document group 1 allergen gene sequence polymorphism in populations of D. farinae and D. pteronyssinus from the USA and Pakistan. We report two novel introns (nt pos 87 and 291) in both species, and the absence of intron 3 in Der p 1. Thirteen silent and one novel non-synonymous mutation (Tryptophan W197 to Arginine R197) were detected in D. farinae. The potential medical significance of the latter mutation is discussed. Two haplotypes of the Der f 1 gene were identified, haplotype 1 (63%) was more frequent than haplotype 2 (18%). Polymorphism in Der f 1 displayed geographical localization, since both haplotypes were present in mite populations from Pakistan whereas haplotype 1 was observed only in the USA. In Der p 1, a silent mutation at nt (aa) position 1011(149) and four non-synonymous mutations at positions 589(50), 935(124), 971(136), 1268(215) were observed. These mutations were reported from many other geographic regions, suggesting that polymorphism in the Der p 1 gene is panmictic. The extent of polymorphism in both genes is substantially lower than that reported previously (0.10-0.16% vs 0.31-0.49%), indicating the need for careful evaluation of potential polymerase errors in studies utilizing RT-PCR.
authors.affiliation: Department of Zoology, Pir Mehr Ali Shah Arid Agriculture University Rawalpindi, Rawalpindi, Pakistan.
authors.forename: Rubaba Hamid
authors.initials: RH
authors.lastname: Shafique
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America; Faculty of Biology, Tyumen State University, Tyumen, Russia.
authors.forename: Pavel B
authors.initials: PB
authors.lastname: Klimov
authors.affiliation: Physiology Laboratory, Department of Zoology, University of the Punjab, Lahore, Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Inam
authors.affiliation: Department of Zoology, Pir Mehr Ali Shah Arid Agriculture University Rawalpindi, Rawalpindi, Pakistan.
authors.forename: Farhana Riaz
authors.initials: FR
authors.lastname: Chaudhary
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America.
authors.forename: Barry M
authors.initials: BM
authors.lastname: OConnor
mesh_terms: D000485:Allergens / Q000235:genetics* / Q000276:immunology; D000818:Animals; D039741:Antigens, Dermatophagoides / Q000235:genetics* / Q000276:immunology; D060829:Arthropod Proteins / Q000235:genetics* / Q000276:immunology; D003546:Cysteine Endopeptidases / Q000235:genetics* / Q000276:immunology; D005796:Genes / Q000235:genetics*; D011110:Polymorphism, Genetic / Q000235:genetics; D039981:Pyroglyphidae / Q000235:genetics* / Q000276:immunology; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D000485:Allergens; D039741:Antigens, Dermatophagoides; D060829:Arthropod Proteins; D003546:Cysteine Endopeptidases; C451159:Dermatophagoides farinae antigen f 1