 - Positive test for allergic sensitization by prick skin testing documented during screening protocol. to allergens associated with current allergen exposure at the time of the rhinovirus RV challenge: e.g., dust mite, Alternaria, andor ragweed for subjects challenged with RV in the fall, or positive tests to tree andor grass pollen allergens for those challenged with RV in the spring. In keeping with the study design goals of inoculating subjects during periods of allergen exposure, sensitization to other allergens e.g., cat or dog will also qualify for enrollment if subjects are currently exposed to these allergens at home. 