Abstract
Eimeria tenella is an intracellular apicomplexan parasite, which infects cecal epithelial cells from chickens and causes hemorrhagic diarrhea and eventual death. We have previously reported the comparative RNA sequence analysis of the E. tenella sporozoite stage between virulent and precocious strains and showed that the expression of several genes involved in mitochondrial electron transport chain (ETC), such as type II NADH dehydrogenase (NDH-2), complex II (succinate:quinone oxidoreductase), malate:quinone oxidoreductase (MQO), and glycerol-3-phosphate dehydrogenase (G3PDH), were upregulated in virulent strain. To study E. tenella mitochondrial ETC in detail, we developed a reproducible method for preparation of mitochondria-rich fraction from sporozoites, which maintained high specific activities of dehydrogenases, such as NDH-2 followed by G3PDH, MQO, complex II, and dihydroorotate dehydrogenase (DHODH). Of particular importance, we showed that E. tenella sporozoite mitochondria possess an intrinsic ability to perform fumarate respiration (via complex II) in addition to the classical oxygen respiration (via complexes III and IV). Further analysis by high-resolution clear native electrophoresis, activity staining, and nano-liquid chromatography tandem-mass spectrometry (nano-LC-MS/MS) provided evidence of a mitochondrial complex II-III-IV supercomplex. Our analysis suggests that complex II from E. tenella has biochemical features distinct to known orthologues and is a potential target for the development of new anticoccidian drugs.
Highlights
Poultry coccidiosis is an intestinal disease caused by infection of the apicomplexan protozoan parasites from the genus, Eimeria
We have previously identified by RNA sequencing analysis that the expression of NDH-2, SDH, malate:quinone oxidoreductase (MQO), and glycerol-3-phosphate dehydrogenase (G3PDH) are upregulated in E. tenella at the stages of sporulating and/or excysted sporozoites [19], which deserved a detailed biochemical study
Five electron transport chain (ETC) dehydrogenases are conserved in the genome of E. tenella, which are the NDH-2, Complex II, MQO, G3PDH, and dihydroorotate dehydrogenase (DHODH) (Figures S1–S5)
Summary
Poultry coccidiosis is an intestinal disease caused by infection of the apicomplexan protozoan parasites from the genus, Eimeria. These parasites produce high economic losses because of decreased chicken growth performance and expensive control systems against the disease. The annual worldwide loss in poultry industries, including egg production, was estimated at up to two billion dollars [1]. The control of coccidiosis is depending on a variety of anticoccidial agents or live attenuated vaccines. These preventive therapies possess severe restricted use in chickens and difficulties to achieve this complete prevention to Eimeria infection. The development of new cost-effective drugs to carry out satisfactory prevention is currently needed
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