FIG 5.

Comparison of anamnestic antibody responses to PA in immunized mice subjected to a late challenge. Groups of mice were immunized three times s.c. with 2 weeks between immunizations with a 50-ng dose of PA adjuvanted with Alhydrogel (0.035 mg) (n = 8) or with Advax (1 mg) plus murabutide (MB) (0.1 mg) (n = 9). Eighteen months postimmunization, mice were challenged with 20 LD₅₀ of aerosolized Sterne strain anthrax spores and then bled at day 2 and day 5 postchallenge for measurement of anti-PA IgG by ELISA.