Ex Vivo Plasmodium malariae Culture Method for Antimalarial Drugs Screen in the Field.

In vitro and ex vivo cultivation of Plasmodium (P) falciparum has facilitated active research into the malaria parasite toward the quest for basic knowledge and the discovery of effective drug treatments. Such a drug discovery program is currently difficult for P. malariae simply because of the absence of in vitro and ex vivo cultivation system for its asexual blood stages supporting antimalarial evaluation. Despite availability of artemisinin combination therapies effective on P. falciparum, P. malariae is being increasingly detected in malaria endemic countries. P. malariae is responsible for chronic infections and is associated with a high burden of anemia and morbidity. Here, we optimized and adapted ex vivo conditions under which P. malariae can be cultured and used for screening antimalarial drugs. Subsequently, this enabled us to test compounds such as artemether, chloroquine, lumefantrine, and quinine for ex vivo antimalarial activity against P. malariae.

Plasmodium malariae and Plasmodium falciparum comparative susceptibility to antimalarial drugs in Mali.

OBJECTIVES: To evaluate Plasmodium malariae susceptibility to current and lead candidate antimalarial drugs. METHODS: We conducted cross-sectional screening and detection of all Plasmodium species malaria cases, which were nested within a longitudinal prospective study, and an ex vivo assessment of efficacy of a panel of antimalarials against P. malariae and Plasmodium falciparum, both PCR-confirmed mono-infections. Reference compounds tested included chloroquine, lumefantrine, artemether and piperaquine, while candidate antimalarials included the imidazolopiperazine GNF179, a close analogue of KAF156, and the Plasmodium phosphatidylinositol-4-OH kinase (PI4K)-specific inhibitor KDU691. RESULTS: We report a high frequency (3%-15%) of P. malariae infections with a significant reduction in ex vivo susceptibility to chloroquine, lumefantrine and artemether, which are the current frontline drugs against P. malariae infections. Unlike these compounds, potent inhibition of P. malariae and P. falciparum was observed with piperaquine exposure. Furthermore, we evaluated advanced lead antimalarial compounds. In this regard, we identified strong inhibition of P. malariae using GNF179, a close analogue of KAF156 imidazolopiperazines, which is a novel class of antimalarial drug currently in clinical Phase IIb testing. Finally, in addition to GNF179, we demonstrated that the Plasmodium PI4K-specific inhibitor KDU691 is highly inhibitory against P. malariae and P. falciparum. CONCLUSIONS: Our data indicated that chloroquine, lumefantrine and artemether may not be suitable for the treatment of P. malariae infections and the potential of piperaquine, as well as new antimalarials imidazolopiperazines and PI4K-specific inhibitor, for P. malariae cure.

Effect of artemether-lumefantrine (Coartem) on cytomegalovirus urine viral load during and following treatment for malaria in children.

BACKGROUND: Artemisinins, commonly used to treat malaria, have shown activity against cytomegalovirus (CMV) in vitro, in an animal model, and in case reports; however, the in vivo anti-CMV activity has not been well investigated. OBJECTIVES: To evaluate whether artemisinins affect CMV shedding among subjects co-infected with CMV and malaria. STUDY DESIGN: A prospective observational study of children in Mali (6 month-10 year) presenting with fever. Urine samples were collected at day 0, 3, and 14 from children treated with artemether-lumefantrine (Coartem(®)) for malaria and those who had other illnesses not treated with Coartem. CMV DNA was quantified using a real-time PCR. Resulting urine viral loads were compared between the groups at three time points. RESULTS: 164 malaria cases and 143 non-malaria comparisons were enrolled. Eighty-one (49%) cases and 88 (62%) comparisons shed CMV at day 0. Day 0 and day 3 viral loads were similar, but at day 14 the median viral load of cases was lower than that of comparisons (360 vs 720 copies/mL or 2.56 vs 2.86 log10), p=0.059. A stratified analysis of day 0 high viral shedders (defined as >1000 copies/mL) showed significantly lower median viral load at day 14 among cases (490 copies/mL, 2.69 log10) vs comparisons (1200 copies/mL, 3.08 log10), p=0.045. CONCLUSION: A high rate of urinary CMV shedding was found in a malaria-endemic area. Among high virus shedders artemether-lumefantrine decreased urine viral load, but the effect was not observed when analysis of both high and low shedders was performed. These results support additional studies of artemisinin dosing and duration in CMV infection.