Advances on aptamers targeting Plasmodium and trypanosomatids.

Aptamers are single-stranded oligonucleotides (ssDNA or RNA) selected from combinatorial libraries by an in vitro process and possess a specific three-dimensional structure depending on its sequence. These molecules are able to recognize and, eventually, alter the activity of their targets by binding directly in a similar way to antibodies. Over the last years, aptamer technology has been used in a wide range of diagnostic and therapeutic applications and, concretely, several strategies are currently being explored using aptamers against Plasmodium and trypanosomatid proteins associated with parasitic diseases which affect hundreds of millions people. One approach tries to block the interaction between the parasite and the host using aptamers targeting host-cell matrix receptors. A second strategy consists in attack the parasite intracellularly targeting heme group or interfering in the intracellular RNA transport. In another strategy, aptamers targeting invariant polypeptides could be used as a specific drug delivery system into the parasite. Finally, aptamers addressed to re-direct the immune response of the infected host are being studied. Other potential use of the aptamers is as biorecognition element in diagnostic systems for parasitic diseases. In this paper, we briefly review how aptamers against Plasmodium and trypanosomatids are discovered, with a focus on recent advances that improve the aptamers properties as a real tool for parasite fighting.