Sebastian Johnston is Professor of Respiratory Medicine at Imperial College London. He is an international leader in the field of respiratory infection and, in particular, has identified the importance of viral exacerbations of airway diseases and their ability to induce airway inflammation, a major cause of hospital admissions in patients with asthma and chronic obstructive pulmonary disease. His discoveries have led to innovative therapeutic approaches, which have included the recent development of inhaled interferon ß for the prevention and treatment of rhinovirus-induced asthma exacerbations. He is Director of the MRC Centre in Allergic Mechanisms of Asthma.