Hindawi Publishing Corporation BioMed Research International Volume 2013, Article ID 832404, 5 pages http://dx.doi.org/10.1155/2013/832404 Research Article The Fold Variant BM4 Is Beneficial in a Therapeutic Bet v 1 Mouse Model Ulrike Pichler, 1 Claudia Asam, 1 Richard Weiss, 1 Almedina Isakovic, 1 Michael Hauser, 1 Peter Briza, 2 Fatima Ferreira, 1,2 and Michael Wallner 1,2 1 Christian Doppler Laboratory for Allergy Diagnosis and erapy, University of Salzburg, 5020 Salzburg, Austria 2 Department of Molecular Biology, University of Salzburg, 5020 Salzburg, Austria Correspondence should be addressed to Fatima Ferreira; fatima.ferreira@sbg.ac.at and Michael Wallner; michael.wallner@sbg.ac.at Received 22 April 2013; Revised 22 August 2013; Accepted 27 August 2013 Academic Editor: Prem L. Bhalla Copyright © 2013 Ulrike Pichler et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background. Specific immunotherapy using recombinant allergens is clinically effective; still wild-type allergens can provoke treatment-induced side effects and oſten show poor immunogenicity in vivo. us, we tested the low IgE-binding, highly immunogenic fold variant BM4 in a Bet v 1 mouse model. Methods. Recombinant BM4 was used as active vaccine ingredient to treat mice sensitized to Bet v 1. As controls, mice were treated with either Bet v 1 or sham, and the humoral as well as cellular immune response was monitored. Moreover, lung function and lung inflammation were analysed. Results. BM4 was more effective than wild-type Bet v 1 in inducing Bet v 1 -specific blocking antibodies as well as IFN- and IL-10 producing T cells. Further, birch pollen induced lung inflammation could be ameliorated significantly by BM4 treatment as demonstrated by a reduction of airway hyperresponsiveness and drastically decreased eosinophil counts in bronchoalveolar lavage fluids. Conclusion. e study outlines the high potential of BM4 as vaccine candidate for the treatment of Bet v 1 -mediated birch pollen allergies. 1. Introduction Pauli et al. impressively demonstrated in a multicenter, ran- domized, double-blind placebo controlled trial that recom- binant Bet v 1 can effectively replace birch pollen extracts in specific immunotherapy (SIT) of birch pollen allergy [1]. Nevertheless, the treatment of subcutaneous SIT is cumber- some, and treatment-induced local adverse reactions were reported during the trial. us, low IgE-binding recombinant allergens or derivatives thereof, which exhibit enhanced immunogenicity, will provide a groundbreaking alternative to wild-type allergens. Such molecules can be engineered to address the innate immune system to effectively redirect the TH2 immune response inherently activated by allergens. As previously published, a fold variant of Bet v 1.0101 (termed Bet v 1 thereaſter), BM4, is suggested to improve efficacy of SIT. Whereas recombinant Bet v 1 induces primarily a TH2 biased immune response, BM4 is able to skew the immune response towards TH1 [2, 3]. To investigate the effects of BM4 as novel therapeutic, we compared the impact of recombinant Bet v 1 and, its fold variant BM4 in a therapeutic mouse model. 2. Material and Methods 2.1. Treatment Model. 8- to 10-week-old female BALB/c mice were purchased from Charles River Laboratories (Sulzfeld, Germany) and used for experiments 4 days aſter arrival (treatment schedule as shown in Figure 1(a)). All animal experiments were conducted according to the guidelines of the Austrian Ministry of Science (BMWF-66.012/0011 - II/10b/2010). Six mice per group were sensitized subcuta- neously (s.c.) with 5 g Bet v 1 adsorbed to Alugel-S (Serva, Heidelberg, Germany) bilaterally in the lumbar region, fol- lowed by three intraperitoneal (i.p.) injections of 25 g Bet v 1, or BM4 in PBS, or PBS alone. Aerosol challenges were performed with nebulized birch pollen extract (10 mg in 10 mL PBS) to induce airway hyperresponsiveness (AHR). ELISA and mediator release assays with murine sera were