Plasmodium vivax: enzyme polymorphism in isolates of Indian origin.

185 isolates of Plasmodium vivax were collected from patients visiting the malaria clinic run by the National Malaria Eradication Programme, Delhi, India. Percoll gradient centrifugation was used to concentrate P. vivax parasites from 0.4 to 0.5 ml of blood collected by finger prick. The parasite concentrate from each isolate was electrophoretically analysed for lactate dehydrogenase (LDH), NADP-dependent glutamate dehydrogenase (GDH), glucose phosphate isomerase (GPI) and adenosine deaminase (ADA). Variations were observed in GPI, GDH and ADA systems. Four electrophoretic forms of GPI and 5 each of GDH and ADA were observed. Electrophoretic mobilities of the different isoenzymic forms in P. vivax were identical to those reported for P. falciparum, indicating that the 2 species cannot be differentiated on the basis of electrophoretic patterns of the 4 enzyme systems studied.