Figure 4

Effect of quinine on maturation and reinvasion of parasites. A/ Sensitivity of FCM29 strain to quinine after 24 or 40 hours of incubation with the drug. Standard microtests were performed in culture. Inhibition of re-invasion/maturation was detected after 20 or 40 hours of culture, respectively. (Cyto20, count of parasites after 20,hours of incubation with drug using TO/HE method, cyto20_inh, per cent of inhibition related to T0 after 20 hours; cyto40, count of parasites after 40 hours of incubation with drug using TO/HE method; cyto40_inh per cent of inhibition related to T0 after 40 hours; RX40 count of parasites after 40 hours of incubation with drug using ₃H-hypoxanthine method; rx40_inh per cent of inhibition related to T0 after 40 hours using ₃H-hypoxanthine method). B/ Stage specific parasitaemia measured in field isolates after 30 hours of culture. Infected RBCs from patients were cultured for 30 hours. Counts of parasites were done separately for ring, trophozoite and schizont stages, respectively. C-D-E-F/ Inhibition of the field isolates by quinine, Per cents of inhibition related to T0 were plotted separately for each isolate using TO/HE detection method after 24 hours of incubation with drug (C-E) or using ₃H-hypoxanthine detection method after 40 hours of incubation with drug (D-F). C-D isolates with maturation to schizonts in culture prior incubation with drug (i.e., B/) during this step quinine is not supposed to be efficient on the parasite and reinvasion can occur with an increase in parasitaemia if not inhibited by the drug; E-F isolates without maturation to schizonts in culture prior incubation with drug (i.e., B/). Quinine was used at 0/50/200/400 nM.