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Mefloquine is an antimalarial drug with schizonticidal activity on blood-stage parasites. Studies of the role of mefloquine on the development of Plasmodium berghei ANKA in Anopheles stephensi have been carried out that showed a dose-dependent effect on the sporogonic cycle of these parasites, with changes in the numbers of oocysts and the extent of sporozoite invasion of salivary glands. In this study, we show that mefloquine-resistant P. berghei ANKA blood stage parasites could be selected through drug pressure during continuous cyclical transmission of Anopheles gambiae s.1.

Irradiated sporozoites are generally thought to elicit protective immune responses that are parasite stage and species specific. But immunization with Plasmodium falciparum sporozoites delivered by the bite of infected mosquitoes protects an average of 60% mice from Plasmodium berghei sporozoite infection. Protection appears to be specific as P. falciparum sporozoite-immunized mice protected against P. berghei remain susceptible to Plasmodium yoelii sporozoite infection. Passively transferred immunoglobulin from P. falciparum sporozoite-immunized mouse serum protected naive mice against challenge with P. berghei sporozoites, indicating that cross-protection is mediated, at least in part, by anti-sporozoite antibody. Antibody-mediated protection may not be due to cross-reaction between P. falciparum and P. berghei CS proteins because mice immunized with the recombinant P. falciparum CS protein repeat vaccine candidate, R32tet32, remain susceptible to P. berghei sporozoite infection.