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About the Authors:
Rubaba Hamid Shafique
* E-mail: [email protected]
Affiliation: Department of Zoology, Pir Mehr Ali Shah Arid Agriculture University Rawalpindi, Rawalpindi, Pakistan
Pavel B. Klimov
Affiliations Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America, Faculty of Biology, Tyumen State University, Tyumen, Russia
Muhammad Inam
Affiliation: Physiology Laboratory, Department of Zoology, University of the Punjab, Lahore, Pakistan
Farhana Riaz Chaudhary
Affiliation: Department of Zoology, Pir Mehr Ali Shah Arid Agriculture University Rawalpindi, Rawalpindi, Pakistan
Barry M. OConnor
Affiliation: Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America
Introduction
Pyroglyphid house dust mites of the genus Dermatophagoides are important sources of allergens in the indoor environment of human dwellings [1], causing allergic diseases such as asthma, rhinitis and atopic dermatitis, in millions of people worldwide [2]. Over 30 different proteins and macromolecules are known to produce IgE-binding reactions in patients allergic to house dust mites [3]. Among these molecules, group 1 allergens of Dermatophagoides farinae and D. pteronyssinus (Der f 1 and Der p 1) dominate overall allergic responses [3]–[5]. Group 1 allergens are cysteine proteases (proteolytic enzymes) [6]–[8], having the ability to induce pro-inflammatory response by breaking lung epithelium [9], [10]. Earlier reports described local variants of group 1 allergens from different geographical regions in Thailand, Korea, China, Australia, and the UK [11]–[20]. Variation data reports come from predicted amino acid sequences based on either amplification from genomic DNA [20], [21] or, more frequently, cDNA libraries obtained through reverse transcriptase polymerase chain reaction (RT-PCR) and subsequent cloning [11], [14], [16], [21]. Because reverse transcriptase is not proof reading [22], it is not surprising that a higher number of mutations were reported in the latter studies.
Amino acid sequence variations can influence IgE binding reactivity of allergens [23]. Single amino acid mutations can alter inflammatory cytokine production of T cells specific for Der p 1 [24], [25]. It is possible that these mutations influence the inherent allergenicity of particular variants and contribute to differential IgE binding frequency by increasing diversity of epitopes [26].
Der f 1 and Der p 1 share 81% amino acid sequence identity [27]–[29] (83%, our data), due to which cross reactivity exists among these two allergens [27]–[29]....