Investigations of the Reasons for the Susceptibility of Schizogony as a Target for Chemotherapeutic Attack in Malaria Parasites.

The research deals with the properties of the intraerythrocytic stages of a stable rat-adapted strain of Plasmodium chabaudi. The parasite shows excellent synchrony but does not appear to produce gametocytes. Lactic acid production is shown to provide a satisfactory growth indicator. This strain does not utilize exogenous adenosine. In approaching the target study of the mechanism of action of pyrimethamine, preliminary observations have been made of the conversion of dihydroorotate to orotate in homogenates of rat liver and the parasitic flagellate, Crithidia fasciculata. It appears that whereas the mammalian system involves a mitochondrial-membrane-bound dehydrogenase, the parasite enzyme is not associated with a membrane and has the properties of a hydroxylase.