Experimental infection and protection against ... - TI Pharma

122 Chapter 6
Figure 1. (A) Parasite density in blood measured by quantitative PCR in 48 volunteers
participating in seven sporozoite challenge trials at the Radboud University Medical
Centre Nijmegen. Grey lines are measurements for individual volunteers, the black line
shows geometric mean parasitemia. Q-PCR cycle threshold above 45 was plotted as zero.
(B) Geometric mean parasite density per multiplication cycle for individual volunteers.
(C) Multiplication rate for every individual by taking the ratio of geometric mean
parasitemia from two cycles. Shown are the ratio of multiplication cycle 2 with cycle 1,
cycle 3 with cycle 2 and square root of the ratio of cycle 3 with cycle 1. Lines indicate
geometric mean of ratios.
Results
Parasite densities showed a consistent cyclical pattern of blood-stage parasite
growth in all volunteers (Figure 1A). The following multiplication cycle intervals
were identified: first cycle from day 6.5 until day 8.5, second cycle from day 8.5
until day 10.5 and third cycle from day 10.5 until day 12.5. All individuals deve-