The invention provides compositions and methods for the prophylaxis or treatment of diseases or disorders in a subject (e.g., a mammal, such as a human) including, e.g., diseases or disorders caused by biological agents, autoimmune diseases, and cancer. The compositions include a delivery vector (e.g., a viral vector, such as an Ad5 vector) encoding an interferon (e.g., IFN-α), and are provided to the subject by, e.g., intranasal or pulmonary administration.
