The pre-patency period for CB immunized mice was significantly greater in the CB sporozoite-challenged group compared to AJ sporozoite-challenged group (P = 0·010) (Table 1, cf rows 1 and 2). This suggests that live sporozoite immunization under MF drug cover with the

CB strain induced a strain-specific, anti-parasitic immunity against homologous CB sporozoite-induced infection, and that this anti-parasitic immunity was already acting before the appearance of a patent High Content Screening blood infection. In mice immunized with AJ strain sporozoites using the same protocol as described earlier and subsequently challenged with sporozoites of either CB or AJ, blood-stage parasites of both

strains tended to appear even earlier following equivalent challenge in naïve mice (Table 1, cf rows 5 and 3, and cf rows 6 and 4), although this effect was not statistically LY294002 mw significant (homologous (AJ sporozoite) challenge vs. mock immunized, P = 0·143; homologous (AJ sporozoite) challenge vs. heterologous (CB sporozoite) challenge, P = 0·403). The course of blood infections in both sporozoite-induced and blood-stage parasite-induced infections in sporozoite-immunized and in mock-immunized control mice are shown in Figure 1. The infection dynamics reveal that sporozoite challenges result in significantly lower parasitaemias HSP90 than blood-stage challenges (F1,50 = 21·96; P ≤ 0·0001). Immunization with CB reduced parasitaemias of

challenge infections significantly more than AJ immunization for both challenge strains (F2,50 = 29·28; P ≤ 0·0001). Moreover, the reduction in parasitaemias following CB immunization were greater for homologous challenges (F2,50 = 6·05; P = 0·004), but this was not the case following immunization with AJ. Specific comparisons of the cumulative proportion of parasitized red blood cells for each type of challenge with its mock-immunized control group supported these findings for the effects of immunization. For CB sporozoite challenge, CB immunization strongly reduced parasitaemias but those achieved following AJ immunization were not significantly different to mock-immunized control infections (Figure 1a; F2,11 = 8·69; P = 0·005). For AJ sporozoite challenge, there was a similar trend in which the lowest parasitaemias were reached after CB immunization (Figure 1b; F2,8 = 0·01; P = 0·009). For CB blood-stage challenge, CB immunization strongly reduced parasitaemia and a slight reduction was achieved following AJ immunization (Figure 1c; F2,12 = 70·57; P ≤ 0·0001).