The collaborative efforts of between research groups have led to significant developments in the pursuit of an effective anti-malarial drug. Drug resistance has become a major concern for the treatment of malaria. Moreover, the chemical diversity of the recognized anti-malarial drugs to date is limited. With regards to the limited chemical diversity, the concern is that combination therapy of drugs based on the existing chemistry backbones will suffer from parasite resistance within a relatively short time (Duffy & Avery, 2012). The development of a novel high-throughput screening method by Duffy and Avery has provided new impetus to the discovery and development of new therapeutic agents to treat malaria.
Duffy and Avery sought to develop an improved high-throughput screening (HTS) method that would the measure of inhibition of parasite growth. This article describes the optimization of a high throughput confocal imaging assay to identify anti-malarial compounds using the DNA-intercalating dye 4’, 6-diamidino-2-phenylindole (DAPI) to monitor the changes in parasite numbers.
The problems with applying the current assay methods to HTS were due to factors of cost, radioactive waste disposal, assay stability and robustness, availability of equipment and quality of data produced. Duffy and Avery decided to adapt a fluorescent DNA dye-based assay that had already been utilised for HTS applications. The previous methods that were used measured the total fluorescence intensity (TFI) outputs and are described to be prone to interferences from the chemical entities that are screened in high-throughput methods.
Duffy and Avery explain the advantage of image output when compared with total fluorescence, is the ability to detect specific isolated areas of fluorescence allowing the elimination of all non-parasite related background readings. By eliminating the background readings compensates for fluorescence activity of compounds that could mask parasite inhibition, thus potentially reducing false-negatives rates.