Immunogenicity of yMSP119-DT conjugates. yMSP119-specific antibody titers (left axis, closed symbols) and the course of parasitemia (right axis, open symbols) in C57BL/10 (left) and B10.S (right) mice immunized with yMSP119, yMSP119-DT (MCS), yMSP119-DT (SPDP), DT, or PBS. Mice were challenged i.v. with 104 P. yoelii YM parasitized red blood cell on day 127. Antibody titers and parasitemias were determined for the duration of the experiment, which concluded on day 155. Termination of the parasitemia and antibody titer curves on the graphs before day 155 indicates that the mouse succumbed to malaria infection and is represented by daggers.