Mice were vaccinated three times at 4 week intervals with the doses of RiVax indicated in the panels. Two weeks after the last vaccination, mice were challenged with aerosolized ricin and lung function was measured as the Penh on days 0, 1, 2, 3, 5, 7, 9, 10, 14. Penh values for days 0, 1, 2, 3 are shown. Black bars = IM, hatched bars = ID, grey bars = control vaccinated mice. * P < 0.05. All data represent 4 experiments of 4 mice each.