SummaryThe kinome of the human malaria parasite Plasmodium falciparum includes two genes encoding mitogen-activated protein kinase (MAPK) homologues, pfmap-1 and pfmap-2, but no clear orthologue of the MAPK kinase (MAPKK) family, raising the question of the mode of activation and function of the plasmodial MAPKs. Functional studies in the rodent malaria model Plasmodium berghei recently showed the map-2 gene to be dispensable for asexual growth and gametocytogenesis, but essential for male gametogenesis in the mosquito vector. Here, we demonstrate by using a reverse genetics approach that the map-2 gene is essential for completion of the asexual cycle of P. falciparum, an unexpected result in view of the non-essentiality of the orthologous gene for P. berghei erythrocytic schizogony. This validates Pfmap-2 as a potential target for chemotherapeutic intervention. In contrast, the other P. falciparum MAPK, Pfmap-1, is required neither for in vitro schizogony and gametocytogenesis in erythrocytes, nor for gametogenesis and sporogony in the mosquito vector. However, Pfmap-2 protein levels are elevated in pfmap-1 -parasites, suggesting that Pfmap-1 fulfils an important function in asexual parasites that necessitates compensatory adaptation in parasites lacking this enzyme.

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the choline analogues displayed strong activity against kinetoplastid parasites, particularly against T. b. brucei. In contrast to their antimalarial activity, they did not act on trypanosomes by disrupting choline salvage or phospholipid metabolism, instead disrupting mitochondrial function, leading to chromosomal fragmentation.

BackgroundWith the introduction of artemisinin-based combination therapy (ACT) in 2005, monitoring of anti-malarial drug efficacy, which includes the use of molecular tools to detect known genetic markers of parasite resistance, is important for first-hand information on the changes in parasite susceptibility to drugs in Ghana. This study investigated the Plasmodium falciparum multidrug resistance gene (pfmdr1) copy number, mutations and the chloroquine resistance transporter gene (pfcrt) mutations in Ghanaian isolates collected in seven years to detect the trends in prevalence of mutations.MethodsArchived filter paper blood blots collected from children aged below five years with uncomplicated malaria in 2003–2010 at sentinel sites were used. Using quantitative real-time polymerase chain reaction (qRT-PCR), 756 samples were assessed for pfmdr1 gene copy number. PCR and restriction fragment length polymorphism (RFLP) were used to detect alleles of pfmdr1 86 in 1,102 samples, pfmdr1 184, 1034, 1042 and 1246 in 832 samples and pfcrt 76 in 1,063 samples. Merozoite surface protein 2 (msp2) genotyping was done to select monoclonal infections for copy number analysis.ResultsThe percentage of isolates with increased pfmdr1 copy number were 4, 27, 9, and 18% for 2003–04, 2005–06, 2007–08 and 2010, respectively. Significant increasing trends for prevalence of pfmdr1 N86 (×2 = 96.31, p <0.001) and pfcrt K76 (×2 = 64.50, p <0.001) and decreasing trends in pfmdr1 Y86 (×2 = 38.52, p <0.001) and pfcrt T76 (×2 = 43.49, p <0.001) were observed from 2003–2010. The pfmdr1 F184 and Y184 prevalence showed an increasing and decreasing trends respectively but were not significant (×2 = 7.39,p=0.060; ×2 = 7.49, p = 0.057 respectively). The pfmdr1 N86-F184-D1246 haplotype, which is alleged to be selected by artemether-lumefantrine showed a significant increasing trend (×2 = 20.75, p < 0.001).ConclusionIncreased pfmdr1 gene copy number was observed in the isolates analysed and this finding has implications for the use of ACT in the country although no resistance has been reported. The decreasing trend in the prevalence of chloroquine resistance markers after change of treatment policy presents the possibility for future introduction of chloroquine as prophylaxis for malaria risk groups such as children and pregnant women in Ghana.