Figure 1.

Titration of sporozoites for intravenous challenge. Naïve BALB/c mice (10 per group) were challenged with titered numbers of P. berghei SPZ by IV (tail vein) injection. Data are compiled from 18 independent challenge experiments. Challenges were arbitrarily considered to have been successful (solid line) when at least 90% of the mice challenged with 300 SPZ were infected (as determined by parasitemia 14 days after challenge) or failed (dotted line) when less than 90% of mice challenged with 300 SPZ were infected. N = 10 mice/group for each experiment. Shown are the average numbers of infected animals from independent challenge experiments ± SEM.