Malaria is one of the most severe public health problems in the world due to the severity of the disease, the number of people affected and the complexity of the life cycle of its causative agent, the protozoan Plasmodium spp.
Although considerable effort has been spent on the development of vaccines, chemotherapy continues to be the main weapon against this disease for the near future. However, resistance to commonly used malaria drugs is spreading and new drugs are required urgently. As a novel alternative to this problem, the present project has been started with the aim of developing aptamers (single chain oligonucleotides with affinity comparable to that of antibodies) able to inhibit or specifically bind to main enzymes of the methylerythritol phosphate pathway (MEP) of isoprenoid synthesis, which are present in the apicoplast, an organ that is found in all phases of Plasmodium spp. This metabolic pathway is ideal for the development of new antimalarial drugs because it is absent in humans and is the unique pathway for the synthesis of isoprenoids in Plasmodium spp.
To this end, we constructed a ssDNA library, which was probed against different homogeneous preparations of recombinant enzymes from the MEP pathway by the method called Systematic Evolution of Ligands by Exponential Enrichment using biotinylated and fluorescein-labeled primers (Flumag-SELEX). To select aptamers of interest, were performed ten cycles of SELEX, then individual aptamers were cloned and sequenced. Nowadays, the selected aptamers are in the process of functional characterization and their effects will be comparing with the available low molecular weight inhibitors. The use of aptamers as therapeutics has still to overcome a number of challenges and difficulties but emerges as an interesting and novel alternative to the shortcomings of traditional treatments.
Acknowledgements: Ministry of Economy and Competitiveness,Spain (Grant BIO2014-52872-R) and Schlumberger Foundation, the Netherlands.