FIG 4.

Lymphocyte proliferation. Groups of BALB/c mice were primed with rDEKnull and boosted with recombinant DEKnull, Sal1, 7.18, P, or MSP1-19. An rSal1 prime-boost group served as a control. Cultured splenocytes harvested 3 weeks after boosting were stimulated with the booster antigen. The T-cell proliferative response was quantified by an MTS assay, and the SI was determined as the ratio of the absorbance at 490 nm of stimulated cells to that of unstimulated cells. Bars represent mean SI values ± standard deviations of triplicate wells. The asterisks indicate significant SI differences between the control group (Sal1-Sal1 prime-boost) and the DEKnull prime–heterologous-boost groups.