Malaria remains one of the most widespread and significant infectious diseases worldwide, causing substantial morbidity and mortality despite ongoing prevention and treatment efforts. Plasmodium falciparum, a causative agent of malaria, has a complex life cycle with stages in both human and Anopheles mosquito hosts. Currently, primary treatment for malaria depends on artemisinin-based combination therapies, however, the emergence of artemisinin resistance independently in both south-east Asia and now Africa threatens the control of this disease. The most prevalent mutations associated with artemisinin resistance in the field are encoded within the parasites’ Kelch13 (K13) gene. During asexual development, K13 protein plays an important role in the formation, stability and function of a double-membraned invagination called the cytostome, whose role is to facilitate uptake of haemoglobin from the host red blood cell into the parasite. This provides the parasite with essential amino acids required for growth and simultaneously releases haem-iron as a bioproduct which is crucial for artemisinin activation. Whilst K13 and it's role in haemoglobin uptake is well studied during asexual development, it's role during sexual blood, mosquito and liver stages of development are yet to be investigated.
Using fluorescence and super resolution microscopy, we show that K13-GFP displays a dynamic localisation pattern throughout gametocytogenesis, with several K13-GFP puncta often converging to form a unique rod-shaped structure in late-stage gametocytes. Similarly, we are using lattice light-sheet and fluorescence microscopy to track the fate of K13-GFP and cytostomes during gamete formation and mosquito stages of development. Using a knock-sideways approach, we are investigating the biological consequences of K13 mislocalisation on cytostome formation and parasite growth during these stages. This work helps to elucidate the biology of cytostomes and determine, for the first time, whether they serve a function other than haemoglobin uptake during other life cycle stages.