Safety and Tolerability Study of rBet v1 SLIT Tablets

Inclusion Criteria: * written consent * Male or female subject from 18 to 60 years old and in general good health * For woman of child bearing potential: * Symptoms of birch pollen induced allergic rhinitis for at least the last 2 years. * Sensitisation to birch pollen as demonstrated with a positive SPT to birch pollen and specific IgE level (birch pollen and r Bet v1) \>0.70 kU/L at screening. * FEV1 at least of 80% of predicted values at screening. * Subject accepting to comply fully with the protocol. Exclusion Criteria: * Past or current disease which as judged by the Investigator, may affect the outcome of this study. * History of life-threatening asthma, * Asthma requiring daily treatment (whatever the pharmaceutical class). * Pregnant or lactating woman. * Subject being treated with inhaled steroids within 4 weeks prior to screening visit or within 12 weeks prior to screening visit. * Subject who previously received desensitisation treatment to birch pollen and/or other betulaceae (e.g., hazel tree, alder) or who plan to start desensitisation treatment during this study. * Symptoms during the treatment phase due to a sensitivity to a second allergen. * Subjects treated with ongoing immunotherapy with another allergen