Stearic Acid as Plasma Replacement for Intracellular in vitro Culture of Plasmodium knowlesi

Abstract

A chloroform extract of Cohn's fraction IV-4 of human plasma successfully replaced whole fraction IV-4 for the intracellular in vitro culture of Plasmodium knowlesi. We are now able to report the successful replacement of monkey plasma by stearic acid.

Some factors affecting the cultivationin vitroof the erythrocytic stages ofPlasmodium knowlesi

“…Identification of the plasma growth factors is imperative for the development of a denned medium for the culture of malaria parasites in vitro. Siddiqui et al (1967) have suggested that plasma can be replaced completely by stearic acid, but this seems unlikely, as in this study the increase in parasite numbers and glucose utilization observed when stearic acid was added to the cultures, even in the presence of lipid-deficient plasma and cholesterol, never reached the levels obtained in the presence of whole plasma. In addition, better results were obtained when the fatty acid was bound to a protein carrier.…”

Biochemistry of Plasmodium (malarial parasites).

“…If normal and P. knowlesi-infected erythrocytes were incubated in vitro with labeled acetate, mevalonate, and cholesterol, only labeled cholesterol was recovered from the parasite membranes (263). (Confirmation of these metabolic studies comes from work [231,263] in which it was shown that stearic acid and cholesterol enhanced the in vitro growth of P. knowlesi.…”

Short-term culture ofPlasmodium knowlesi

“…This must presumably be attributed to differences in the composition of normal serum and donor red cells (parasitized and nonparasitized). Cultivation of parasites in synthetic media (Siddiqui, Schnell & Geiman, 1967) has not as yet proved successful in the hands of others (Trigg, 1969). It is evident, however, that precise definition of cultural conditions must be based upon in vitro growth of malaria parasites in a cell-free medium having a known composition.…”