FIG. 2.
Efficacy of i.n. vaccination with PA-FIS in the mouse model of respiratory anthrax. Mice were immunized with either PA-FIS or PA alone through the i.n. route (i.n.×2). Three weeks after the booster injection all animals (eight per control group, nine per assay group) were infected i.n. with 9 LD50 of B. anthracis 9602 spores. The mice were observed for 6 days after exposure. The number of mice in the PA-FIS group surviving the challenge was significantly greater than that in either the control group (**, P = 0.0016) or the PA group (*, P = 0.045). The number of mice in the PA group surviving the challenge was significantly greater than that in the control group (*, P = 0.036).