FIG 6.

Role of CD4⁺ and CD8⁺ T cells in protective immunity induced by a 10⁷ P. yoelii 17X F3 + PHAD liposomal blood-stage vaccine. Groups of BALB/c mice (n = 5/group) were immunized with three doses of the F3 + PHAD liposome vaccine containing 10⁷ P. yoelii 17X pRBCs and challenged 1 month after the final vaccine dose with 10⁵ P. yoelii 17X pRBCs. Vaccinated mice received injections of rat Ig, anti-CD4⁺, or anti-CD8⁺ antibodies on days −2, −1, 4, and 8 relative to the challenge on day 0. A naive control group that only received the challenge was also included. (A) Parasitemias were monitored by blood films every second day after challenge. (B) Mice were monitored daily after challenge and euthanized if indicated by their clinical score or a weight loss of >15% postchallenge. (C) Hemoglobin levels were measured using a Hemocue201⁺ Analyser. The data are presented as means ± the SEM. +, Mice that were euthanized based on their clinical score or a weight loss of >15% postchallenge.