Search

Introduction Allergenspecific immunotherapy (AIT) represents a curative approach for treating allergies. In the tropical and subtropical regions of the world, Blomia tropicalis (Blo t 5 and Blo t 21) is the likely dominant source of indoor allergens. Aim To generate a hypoallergenic Blo t 5/Blo t 21 hybrid molecule that can treat allergies caused by B tropicalis. Methods Using in silico design of B tropicalis hybrid proteins, we chose two hybrid proteins for heterologous expression. Wildtype Blo t 5/Blo t 21 hybrid molecule and a hypoallergenic version, termed BTH1 and BTH2, respectively, were purified by ion exchange and size exclusion chromatography and characterized by physicochemical, as well as in vitro and in vivo immunological, experiments. Results BTH1, BTH2 and the parental allergens were purified to homogeneity and characterized in detail. BTH2 displayed the lowest IgE reactivity that induced basophil degranulation using sera from allergic rhinitis and asthmatic patients. BTH2 essentially presented the same endolysosomal degradation pattern as the shortened rBlo t 5 and showed a higher resistance towards degradation than the fulllength Blo t 5. In vivo immunization of mice with BTH2 led to the production of IgG antibodies that competed with human IgE for allergen binding. Stimulation of splenocytes from BTH2immunized mice produced higher levels of IL10 and decreased secretion of IL4 and IL5. In addition, BTH2 stimulated Tcell proliferation in PBMCs isolated from allergic patients, with secretion of higher levels of IL10 and lower levels of IL5 and IL13, when compared to parental allergens. Conclusions and Clinical Relevance BTH2 is a promising hybrid vaccine candidate for immunotherapy of Blomia allergy. However, further preclinical studies addressing its efficacy and safety are needed. (VLID)5815269