[Evaluation of in vitro drug sensitivity of antimalarials for Plasmodium falciparum using a colorimetric assay (DELI-microtest)].

The DELI-microtest (Double-Site Enzyme Linked LDH Immunodetection) is a colorimetric method for determination of Plasmodium falciparum in vitro sensitivity to antimalarial drugs. This method is based on the capture of the specific lactate deshydrogenase of Plasmodium falciparum (pLDH) using 2 monoclonal antibodies which recognize 2 different sites of the enzyme. The second monoclonal antibody is biotinylated and may catch a peroxidase-labelled streptavidine and develop a colorimetric reaction in the presence of peroxidase substrate. The level of pLDH released by parasite growth is determined by the measure of optical densities. An excellent correlation has been observed between the IC50's obtained using the DELI-microtest and the classical isotopic microtest, and the high sensitivity of the DELI-microtest can be used to measure the IC50's for isolates with parasitemia as low as 0.005%. It is easier and faster to process than isotopic microtest in field conditions. In addition, due to high sensitivity of the DELI-microtest, isolates with a low parasitemia may be included in the studies.