The role of autophagy in protozoan infections.

Autophagy is a conserved, lysosome-dependent degradation system that is used by a wide variety of eukaryotes; during autophagy, intracellular substances are transported to lysosomes for degradation, and thus, autophagy plays a crucial role in cell survival under stress conditions such as starvation and hypoxia. Additionally, cells can eliminate foreign pathogens, such as parasites, bacteria, and viruses, via autophagic clearance. Protozoa are categorized as either intracellular parasitic protozoa or extracellular parasites, which are mostly zoonotic pathogens that pose significant threats to public health. In recent years, research on the mutual influences of autophagy and protozoa has focused mainly on Toxoplasma and Plasmodium, with less focus on extracellular parasitic protozoa. In this review, we discuss the crucial role of autophagy in maintaining the dynamic equilibrium between host elimination of extracellular and intracellular parasites and parasitic exploitation of the host.