Example model predictions for blood parasite levels in a subset of individuals.

<p>Black bullets represent data points; black triangles are observations below the detection limit (dashed line). The solid black line represents the posterior mean. The shaded band around it represents the 2.5^th and 97.5^th percentiles of the predicted parasite concentrations, based on 8000 draws from the posterior distribution. Panel headers refer to unique identifiers for CHMI volunteers, which can also be found in the data (<a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1005255#pcbi.1005255.s008" target="_blank">S1 File</a>).</p

Study characteristics.

<p>Study characteristics.</p

Simulated vaccine trial power to detect a statistically significant difference between an intervention and control group (T-test assuming unequal variances, setting <i>α</i> = 0.05).

<p>Simulations were performed for each combination of vaccine type (erythrocytic or hepatic), efficacy (50%, 60%, 70%, 80%, or 90% reduction in first-generation parasite loads or parasite multiplication rate), variation in efficacy between individuals (standard deviation or SD), and the frequency of blood samples taken: one per two days (8am or 4pm), or one (8am), two (8am, 4pm), or three (8am, 4pm, 10pm) per day. Power calculations for a wider range of vaccine efficacy (30%–95%) can be visualized with the graphical user interface in <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1005255#pcbi.1005255.s009" target="_blank">S2 File</a>.</p

Parameter estimates for parasite kinetics in mosquito-based, controlled human malaria infection.

<p>Parameter estimates for parasite kinetics in mosquito-based, controlled human malaria infection.</p

Matrix scatter plot of random effects for sources of inter-individual variation.

<p>Random effects (x-axes and y-axes) pertain to the average time of appearance of first generation blood parasites, the number of first cycle parasites, the multiplication rate of blood parasites, and the log-odds ratio of an individual having parasites detected during blood microscopy, adjusted for predicted parasite levels. Within each panel, each bullet represents the point estimate for one CHMI volunteer (<i>N</i> = 56), based on the mean of 8000 draws from the posterior.</p

Phenotypic analyses CD44hi T-cells.

<p>(A) Gating strategy. After lymphocytes gating based on forward-scatter (FSC) and side-scatter (SSC) properties, CD4+ and CD8+ T cells were selected. Total memory T cells were gated based on high CD44 expression. T cells with effector memory (T_EM) and central memory (T_CM) phenotype were identified based on CD62L expression. (B) CD8+CD44hi and CD4+CD44hi T-cell pool at day 40 post-immunization with high or lose dose. Composition of the CD8+CD44hi and CD4+CD44hi T-cell pool was assessed in the liver (left panel), spleen (central panel) or PBMC (right panel) of mice immunized by high and low dose of RAS or CPS. Results are from 2 independent experiments (n_RAS = 10; n_CPS = 10; n_naïve = 13) and cells from individual mice assayed. Error bars represent standard error of the mean (SEM). * = p<0.05, ** = p<0.005, *** = p<0.0001.</p

IFNγ response by liver and spleen CD8+CD44hi T cells.

<p>At day 62, liver and spleen cells collected from immune RAS or CPS mice were stimulated for 24 hours ex vivo with cryo-conserved <i>Pb</i>spz. IFNγ response was assessed by intracellular cytokine staining prior to flow-cytometry measurement (2 experiments). The percentage of IFNγ+ lymphocytes upon stimulation with PMA and ionomycin was similar between RAS (n = 15), CPS (n = 10) and naïve (n = 6) mice in the liver (6.9%, 5.2%, 5.1%) or spleen (1.33%, 1.65%, 1.1%). * = p<0.05, ** = p<0.001.</p

Long-term RAS and CPS^a protection following <i>P. berghei</i> sporozoite challenge^b.

a<p>CPS mice received 24-days chloroquine treatment. Three of the six naïve mice challenged at t = 3months receive the same chloroquine treatment.</p>b<p>Mice were challenged by i.v. injection of 10.000 WT sporozoites. Protection was defined as negative blood-smears at day 21 after challenge.</p

Sporozoite and blood-stage specific IgG.

<p>Plasma were collected from mice immunized by RAS or CPS before (C-1) and 6 to 21 days after (C+6; C+21) challenge. Levels of anti-sporozoite or anti-blood-stage IgG antibodies were determined by ELISA (n_RAS = 5; n_CPS = 5; n_naïve = 9). Error bars represent standard error of the mean (SEM). ** = p<0.005, *** = p<0.0001.</p

RAS and CPS^a protection upon <i>P. berghei</i> sporozoite challenge^b.

a<p>CPS mice received 24-days chloroquine treatment. All immunized mice were challenged 17 days after CQ treatment.</p>b<p>Cumulative data from three experiments. In two experiments, mice were challenged by i.v. injection of 10.000 WT sporozoites. In one experiment, mice were challenged by bites of 5–11 infected mosquitoes. Protection was defined as negative blood-smears at day 21 after challenge.</p