Antisense oligonucleotides targeting malarial aldolase inhibit the asexual erythrocytic stages of Plasmodium falciparum.

A major obstacle in the global effort to control malaria is the paucity of anti-malarial drugs. This is compounded by the continuing emergence and spread of resistance to old and new anti-malarial drugs in the malarial parasites. Here we describe the anti-malarial effect of phosphorothioate antisense (AS) oligodeoxynucleotides (ODNs) targeting the aldolase enzyme of Plasmodium falciparum, using the asexual blood stages of the parasite grown in vitro. The blood stages of P. falciparum depend almost entirely on the energy produced by their own glycolysis. Aldolase, the fourth enzyme of the glycolytic pathway, is highly upregulated during the malarial 48-h life cycle. We found that the mRNA of this enzyme can be inhibited, in a sequence specific manner, using AS-ODN to the splice sites on the pre-mRNA of malarial aldolase. At the enzyme level, both specific AS-ODNs for the splice sites, as well as for the translation initiation site on mature mRNA, can inhibit aldolase enzyme activity within the trophozoites of P. falciparum. Furthermore, this downregulation of the malarial aldolase results in a reduction in the production of ATP within the parasite. Finally, the treatment reduces parasitemia. In summary, AS-ODNs targeting the aldolase gene of P. falciparum can interfere with the blood-stage life cycle of this parasite in vitro by inhibiting the expression of the enzyme aldolase which results in decreased malarial glycolysis and energy production. Thus, we conclude that blockade of the expression of malarial glycolytic enzymes using specific AS-ODNs has the potential of a new anti-malarial strategy.