Oleic acid is indispensable for intraerythrocytic proliferation of Plasmodium falciparum

Serum-derived fatty acids are essential for the intraerythrocytic proliferation of Plasmodium falciparum in humans. We previously reported that only limited combinations of fatty acids can support long-term parasite culture, and palmitic acid (C(16 : 0))/oleic acid (C(18 : 1, n-9)), palmitic acid (C(16 : 0))/vaccenic acid (C(18 : 1, n-7)), or stearic acid (C(18 : 0)) are required in these combinations, implying that these fatty acids are key molecules for intraerythrocytic parasite growth (Mi-Ichi et al. 2006). Here, we analysed profiles of parasitaemia changes as well as morphologies during the erythrocytic cycle and confirmed the importance of C(16 : 0) and C(18 : 1, n-9). We also provide evidence that C(18 : 1, n-9) but not other C18 monoenoic or dienoic acids maintain the synchronicity of parasite development in serum-free medium when paired with C(16 : 0), resulting in maintained exponential growth. Thus, C(18 : 1, n-9) is indispensable for the intraerythrocytic proliferation of P. falciparum.