Isoenzyme variation in schizonts of Plasmodium vivax from Burma

Fifteen isolates of blood containing Plasmodium vivax were collected from hospital in-patients in Rangoon and the schizonts were harvested for starch gel electrophoresis of the following parasite isoenzymes--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) (EC.1.1.1.43). Variation was found only in GPI. The other three isoenzymes appeared to be invariant in all the isolates. Forms of GPI were recorded in two isolates of P. vivax which differed from those reported for P. falciparum; these new forms were designated GPI-4 and GPI-5.