Isoenzyme characterization of chloroquine-resistant isolates of Plasmodium falciparum from Burma

Sixty isolates of Plasmodium falciparum collected from hospital in-patients in Rangoon and out-patients from villages near Rangoon were tested in vitro for chloroquine sensitivity and then cultured to carry out starch gel electrophoresis of the following parasite enzyme: glucose phosphate isomerase (GPI) (EC.5.3.1.9.), NADP-dependent glutamate dehydrogenase (GDH) EC.1.4.1.4), lactate dehydrogenase (LDH) (EC.1.1.1.27) and 6-phosphogluconate dehydrogenase (6PGD) (E.C.1.1.1.44). Variations were observed in three (GPI, GDH and LDH) of the four enzymes examined. Three forms of parasite GPI, two forms of parasite GDH, two forms of parasite LDH and only one form of parasite 6PGD were identified. Enzyme polymorphism was more common in isolates with higher resistance to chloroquine. One isolate with parasite GDH-2 and six isolates with parasite LDH-2 were recorded from chloroquine-resistant cases.