Critical Steps of Plasmodium falciparum Ookinete Maturation

Abstract

The egress and fertilization of <i>Plasmodium</i> gametes and development of a motile ookinete are the first crucial steps that mediate the successful transmission of the malaria parasites from humans to the <i>Anopheles</i> vector. However, limited information exists about the cell biology and regulation of this process. Technical impediments in the establishment of <i>in vitro</i> conditions for ookinete maturation in <i>Plasmodium falciparum</i> and other human malaria parasites further constrain a detailed characterization of ookinete maturation. Here, using fluorescence microscopy and immunolabeling, we compared <i>P. falciparum</i> ookinete maturation in <i>Anopheles coluzzii</i> mosquitoes <i>in vivo</i> and in cell culture <i>in vitro</i>. Our results identified two critical steps in ookinete maturation that are regulated by distinct mosquito factors, thereby highlighting the role of the mosquito environment in the transmission efficiency of malaria parasites.