Loida R. MedinaNat MalainualJohn Donnie A. RamosUniversity of Santo Tomas, ManilaMahidol University2018-12-212019-03-142018-12-212019-03-142017-12-01Asian Pacific Journal of Allergy and Immunology. Vol.35, No.4 (2017), 203-211222886940125877X2-s2.0-85041518808https://repository.li.mahidol.ac.th/handle/20.500.14594/42708© 2017, Allergy and Immunology Society of Thailand. All rights reserved. Background: Blo t 5, a major allergen from the house dust mite Blomia tropicalis had been identified as an important trigger of allergic diseases. Effects of sequence variations to the IgE binding activity of Blo t 5 remain unclear. Objective: The study determined gene polymorphisms of Blo t 5, expressed the recombinant Blo t 5 allergen in E. coli system and determined its IgE reactivity in house dust mite allergic Filipino patients. Method: Gene polymorphism was determined using Polymerase Chain Reaction and DNA sequencing. Recombinant Blo t 5 was expressed as a GST-fusion protein in E. coli and purified by affinity chromatography. IgE-binding activity of 230 age- and sex-matched allergic and non-allergic subjects was subjected to Enzyme-linked Immunosorbent Assay and Western blot analysis. Results: Five polymorphic variants of Blo t 5 were identified with 26 DNA base and 12 amino acid substitutions thus implying a high degree of sequence diversity. Of the 115 cases, 68.70% and 59.13% showed reactivity to Blo t extract and rBlo t 5 respectively. Total and specific IgE levels of allergic and non-allergic subjects differ significantly (p<0.0001). Conclusions: Blo t 5 gene exhibits polymorphic variants with predicted amino acid sequences resulting to changes in its IgE epitopes. These polymorphisms may suggest variability of allergenic properties of Blo t 5. The incorporation of the Blo t 5 variants in the panel of diagnostic allergens and immunotherapy is highly recommended.Mahidol UniversityImmunology and MicrobiologyArticleSCOPUS10.12932/AP0794