In-vitro Activity of Artemether, Lumefantrine, Dihydroartemisinin and Piperaquine against 3D7 and W2 Plasmodium Falciparum Reference Clones in a Formulated Transport Medium and EDTA

Abstract

Introduction: in vitro drug sensitivity relies on the growth of plasmodium in the presence of the antimalarials. These fresh isolates brought in for assay from collection sites normally not near the laboratory require a medium to keep the parasites viable in order to produce results which are a representation of the field situation in terms of drug susceptibility. However, factors  such  as  mixed  infection  of  drug resistant and  sensitive  parasites occurring in most field isolates can  influence  drug  test  outcome because they have different drug susceptibilities, thus there is a need of using clones which have identified these drug resistant sub populations to prevent treatment failures, misidentification of a populations susceptibility profile and also in any evaluation procedure so as to provide accurate test results. Objective: This study validated the use of a formulated transport medium (TM) by assaying clones which have been culture adapted in the lab for 50% inhibitory concentrations (IC₅₀) against four antimalarials using SYBR Green 1 in vitro assay. Method: These clones (3D7 and W2) were revived and culture adapted for assay. Prior to subjecting them to drugs, they were exposed to 2ml formulated TM and the conventional EDTA anticoagulant in 5ml vacutainer tubes to act as control. Results: Both clones gave successful assays with moderate RFU values of between 2000 to 4000 parasites obtained by 3D7clone while W2 had RFU values as high as 20,000 parasites. However, their curves converged into discernible dose-response curves. Similarity was detected with no significant difference (P >0.05) observed in the medians inhibitory concentration 50 (IC₅₀) between samples in the EDTA anticoagulant and TM however, samples in EDTA generally had higher IC₅₀ values. Conclusion: This study concludes that the formulated TM holds promise for future use.