Two Center Evaluation of the Safety and Efficacy of Topical Nasal rEV131 Versus rEV131 Vehicle (Placebo)in the Prevention of the Signs and Symptoms of Allergic Rhinitis Induced by Nasal Allergen Challenge

The purpose of this study is to see whether rEV131 when given as a nasal spray in a single dose to each nostril is safe and can reduce the signs and symptoms of allergic rhinitis (hay fever) caused by an allergen challenge. All patients enrolled will be known to be allergic to ragweed pollen and will be given ragweed pollen extract in both nostrils 30 minutes after either rEV131 or innactive vehicle (placebo). The signs and symptoms (sneezing, itching, stuffiness and runny nose) will each be given a score from 0 to 3 by the patient and these will be added together and the combined scores from patients treated with rEV131 will be compared with those who received placebo.