DRUG RESPONSE AND GENETIC-CHARACTERIZATION OF PLASMODIUM-FALCIPARUM CLONES RECENTLY ISOLATED FROM A SUDANESE VILLAGE

We have isolated 20 clones of Plasmodium falciparum from isolates from patients attending a village clinic in Sudan during 10 d in October-N ovember 1989. The clones were genetically diverse, having highly varia ble molecular karyotypes and a wide range of drug responses. Chloroqui ne-sensitive (50% inhibitory concentration [IC50] in the 4-15 nm range ) and chloroquine-resistant clones (IC50 in the 40-95 nm range) co-exi sted in the population, but no obvious amplification of the P-glycopro tein homologue gene, Pgh1 (previously known as the multi-drug resistan ce gene, mdr1) marked the chloroquine-resistant clones. Chloroquine re sistance was reversible by verapamil in these clones, although they va ried in their susceptibility to verapamil alone. These observations in dicate that the biochemical characteristics of the Sudanese chloroquin e-resistant P. falciparum are similar to those reported from south-eas t Asian and Latin American isolates, which is consistent with there be ing a similar molecular basis for this phenomenon.