Figure 3. Pre-erythrocytic immunity following CPS immunization requires high doses of sporozoites.
Liver parasite burden was determined 42 hr after mosquito bite challenge as copy number of P. chabaudi-specific 18S rRNA. (A) Mice were CPS immunized three times (i1, i2, i3) with P. chabaudi AS-infected mosquito bites under chloroquine (CQ) cover (CPS (Bite)) and challenged (C) 96–104 days after immunization by bites of P. chabaudi AS-infected mosquitoes (pooled data from three independent experiments; naive infection controls (−) n = 25, CPS (Bite) n = 35). (B) 100 or 10,000 untreated or irradiated (Irr.) P. chabaudi CB sporozoites (spz) were injected iv three times under CQ cover. Mice were challenged 96 days after immunization by bites of P. chabaudi CB-infected mosquitoes (naive infection controls (−) n = 12, all other groups n = 20). All data are displayed relative to the mean of corresponding liver parasite burden of naïve infection controls and presented as mean ± SEM, (A) Mann–Whitney test: no significant difference between the groups; (B) Kruskal Wallis with Dunn's multiple comparisons test *p ≤ 0.05, ***p ≤ 0.001.