Eimeria proteins: order amidst disorder

Abstract

Apicomplexans are important pathogens that cause severe infections in humans and animals. The biology and pathogeneses of these parasites have shown that proteins are intrinsically modulated during developmental transitions, physiological processes and disease progression. Also, proteins are integral components of parasite structural elements and organelles. Among apicomplexan parasites, Eimeria species are an important disease aetiology for economically important animals wherein identification and characterisation of proteins have been long-winded. Nonetheless, this review seeks to give a comprehensive overview of constitutively expressed Eimeria proteins. These molecules are discussed across developmental stages, organelles and sub-cellular components vis-à-vis their biological functions. In addition, hindsight and suggestions are offered with intention to summarise the existing trend of eimerian protein characterisation and to provide a baseline for future studies. Graphical Abstract

Eimeria falciformis secretes extracellular vesicles to modulate proinflammatory response during interaction with mouse intestinal epithelial cells

“…2 ) suggests that specific protein could be secreted via two or more secretory pathways during host-parasite interactions. The secretion of Hsp70 by Eimeria species is associated with sporozoite formation, pathogenicity, protective immunity and response to stress [ 5 , 58 , 59 ]. Hsp70 has also been reported among EV proteins from C. parvum, N. caninum , T. gondii , Leishmania and Trypanosoma species [ 7 ].…”

“…Ef SEV proteases are likely to play important roles in E. falciformis sporozoite invasion, evasion of immune cells [ 60 ], developmental regulation and virulence, as revealed in other Apicomplexa [ 61 ], as well as degrading the cell matrix of host tissue [ 62 ]. Also, proteases are transcriptional regulators of E. tenella, Plasmodium and T. gondii life-cycles [ 5 , 63 ] and, more importantly, the invasion of Eimeria sporozoites is accompanied by proteolytic shedding of surface adhesins mediated by protease [ 64 ] (Fig. 2 ).…”

“…Previous studies have described and characterized the secretion of extracellular vesicles (EVs) and vesicle-free (VF) molecules from parasitic protozoa and helminths [ 2 , 3 ] as well as from parasite-infected host cells [ 4 ]. Similarly, there have been several studies on the secretion, characterization and proteomic profiling of Eimeria sporozoite proteins triggered by thermal, chemical and mechanical stressors [ 5 ]. In addition, VF molecules have been induced and characterized from protozoan parasites in various modified mediums and by physicochemical stressors [ 5 , 6 ].…”

“…Similarly, there have been several studies on the secretion, characterization and proteomic profiling of Eimeria sporozoite proteins triggered by thermal, chemical and mechanical stressors [ 5 ]. In addition, VF molecules have been induced and characterized from protozoan parasites in various modified mediums and by physicochemical stressors [ 5 , 6 ]. Pathogenic protozoan EVs activated by chemical stressors and serum-starved media have also been characterized and profiled [ 7 ].…”

“…In general, parasitization of the host cells by apicomplexan parasites involves gliding motility, cellular attachment, invasion and spontaneous formation of excretory/secretory products with which apicomplexans modulate host cell responses [ 10 , 26 – 28 ]. However, E. falciformis sporozoite proteins secreted during interaction with the host IECs have not been described [ 5 ]. Also, the secretion of parasite-derived EVs has not been characterized in Eimeria spp.…”