Kinetics of induction of rabbit anti-Pfs25 antibody. Groups of 4 rabbits were immunized with (i) 80 μg of Pfs25 adsorbed onto alum (blank bars), or (ii) 80 μg of Pfs25 formulated with Montanide ISA720 (hatched bars). Animals were immunized on days 0, 28 and 56, and bled on days 0, 28, 42 and 70. Sera were tested for anti-Pfs25 antibody concentration by ELISA relative to a standard rabbit anti-Pfs25 serum which has 100,000 units. ELISA values of individual rabbits are plotted and the geometric mean ± SE for the group are also shown. On day 70, the antibody units of the Pfs25-ISA group are significantly higher than those of the Pfs25-alum group (Mann-Whitney U-test, p < 0.0001).