DNA aptamers for malaria diagnosis - from crystal structure to clinical application

Abstract

DNA aptamers have the potential to disrupt medical diagnostics by replacing antibodies for molecular recognition. However, few aptamers have reached the stage of clinical application. A key challenge is discovery of suitable aptamer-target pairs and how best to link the binding event to a diagnostic signal particularly for point-of-care tests. Here, we present our work to develop DNA aptamers for point-of-care malaria diagnosis. We discovered aptamers against Plasmodium lactate dehydrogenase as a general Plasmodium biomarker and against histidine-rich protein 2 as a Plasmodium falciparum specific biomarker. We have solved the crystal structure of Plasmodium lactate dehydrogenase aptamer in complex with its target, making this one of the best characterized aptamer-target pairs. Furthermore, we have integrated aptamers into an assay termed aptamer-tethered enzyme capture (APTEC) which is able to diagnose malaria in stored clinical patient blood samples. Work is ongoing using microarrays to optimize aptamer affinity and we are rapid prototyping 3D printed aptamer-enabled devices with a view to developing a point-of-care diagnostic test that is inexpensive, robust, sensitive and specific for the developing world.