A hybrid of two major Blomia tropicalis allergens as an allergy vaccine candidate

• Published in: Clinical and experimental allergy Vol. 50; no. 7; pp. 835 - 847
• Main Authors: Silva, Eduardo Santos, Aglas, Lorenz, Pinheiro, Carina Silva, Andrade Belitardo, Emília M. M., Silveira, Elisânia Fontes, Huber, Sara, Torres, Rogério Tanan, Wallner, Michael, Briza, Peter, Lackner, Peter, Laimer, Josef, Pacheco, Luis Gustavo C., Cruz, Álvaro A., Alcântara‐Neves, Neuza Maria, Ferreira, Fatima
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01-07-2020; John Wiley and Sons Inc
• Subjects: allergenicity; Allergens; allergen‐specific immunotherapy; Allergic rhinitis; Allergies; Asthma; Blo t 5 antigen; Cell proliferation; Degranulation; house dust mite; hypoallergen; immunogenicity; Immunoglobulin E; Immunoglobulin G; Immunotherapy; Original; Patients; Splenocytes; vaccine candidate; Vaccines; house dust mite; vaccine candidate; allergenicity; hypoallergen; immunogenicity; allergen-specific immunotherapy
• ISSN: 0954-7894; 1365-2222
• DOI: 10.1111/cea.13611

Introduction
Allergen‐specific 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. Wild‐type 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 full‐length 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 BTH2‐immunized mice produced higher levels of IL‐10 and decreased secretion of IL‐4 and IL‐5. In addition, BTH2 stimulated T‐cell proliferation in PBMCs isolated from allergic patients, with secretion of higher levels of IL‐10 and lower levels of IL‐5 and IL‐13, when compared to parental allergens.
Conclusions and Clinical Relevance
BTH2 is a promising hybrid vaccine candidate for immunotherapy of Blomia allergy. However, further pre‐clinical studies addressing its efficacy and safety are needed.