Effects of diclazuril on the expression of enolase in second-generation merozoites of Eimeria tenella

Comparative proteomic analysis across the developmental stages of the Eimeria tenella

Eimeria tenella is the main pathogen responsible for coccidiosis in chickens. The life cycle of E. tenella is, arguably, the least complex of all Coccidia, with only one host. However, it presents different developmental stages, either in the environment or in the host and either intracellular or extracellular. Its signaling and metabolic pathways change with its different developmental stages. Until now, little is known about the developmental regulation and transformation mechanisms of its life cycle. In this study, protein profiles from the five developmental stages, including unsporulated oocysts (USO), partially sporulated (7 h) oocysts (SO7h), sporulated oocysts (SO), sporozoites (S) and second-generation merozoites (M2), were harvested using the label-free quantitative proteomics approach. Then the differentially expressed proteins (DEPs) for these stages were identified. A total of 314, 432, 689, and 665 DEPs were identified from the comparison of SO7h vs USO, SO vs SO7h, S vs SO, and M2 vs S, respectively. By conducting weighted gene coexpression network analysis (WGCNA), six modules were dissected. Proteins in blue and brown modules were calculated to be significantly positively correlated with the E. tenella developmental stages of sporozoites (S) and second-generation merozoites (M2), respectively. In addition, hub proteins with high intra-module degree were identified. Gene Ontology (GO) and Kyoto Encyclopedia of Gene and Genomes (KEGG) pathway enrichment analyses revealed that hub proteins in blue modules were involved in electron transport chain and oxidative phosphorylation. Hub proteins in the brown module were involved in RNA splicing. These findings provide new clues and ideas to enhance our fundamental understanding of the molecular mechanisms underlying parasite development.

Diclazuril-induced expression of CDK-related kinase 2 in the second-generation merozoites of Eimeria tenella

Diclazuril is a classic anticoccidial drug. The key molecules of diclazuril in anticoccidial action allows target screening for the development of anticoccidial drugs. Cyclin-dependent kinases (CDK) are prominent target proteins in apicomplexan parasites. In this study, a diclazuril anticoccidiosis animal model was established, and the transcription and translation levels of the CDK-related kinase 2 of Eimeria tenella (EtCRK2) were detected. mRNA and protein expression levels of EtCRK2 decreased in the infected/diclazuril group compared with those in the infected/control group. In addition, immunofluorescence analysis showed that EtCRK2 was localised in the cytoplasm of the merozoites. The fluorescence intensity of EtCRK2 in the infected/diclazuril group was significantly weaker than that in the infected/control group. The anticoccidial drug diclazuril against E.tenella affects the expression pattern of EtCRK2 molecule, and EtCRK2 is a potential target for new drug development.

In Vitro Transcriptional Response of Eimeria tenella to Toltrazuril Reveals That Oxidative Stress and Autophagy Contribute to Its Anticoccidial Effect

Intestinal coccidiosis is a common parasitic disease in livestock, caused by the infection of Eimeria and Cystoisospora parasites, which results in great economic losses to animal husbandry. Triazine compounds, such as toltrazuril and diclazuril, are widely used in the treatment and chemoprophylaxis of coccidiosis. Unfortunately, widespread drug resistance has compromised their effectiveness. Most studies have focused on prophylaxis and therapeutics with toltrazuril in flocks, while a comprehensive understanding of how toltrazuril treatment alters the transcriptome of E. tenella remains unknown. In this study, merozoites of E. tenella were treated in vitro with 0.5 μg/mL toltrazuril for 0, 1, 2 and 4 h, respectively. The gene transcription profiles were then compared by high-throughput sequencing. Our results showed that protein hydrolysis genes were significantly upregulated after drug treatment, while cell cycle-related genes were significantly downregulated, suggesting that toltrazuril may affect parasite division. The expression of redox-related genes was upregulated and elevated levels of ROS and autophagosomes were detected in the parasite after toltrazuril treatment, suggesting that toltrazuril may cause oxidative stress to parasite cells and lead to its autophagy. Our results provide basic knowledge of the response of Eimeria genes to toltrazuril and further analysis of the identified transcriptional changes can provide useful information for a better understanding of the mechanism of action of toltrazuril against Eimeria.

Nano-encapsulation of halofuginone hydrobromide enhances anticoccidial activity against Eimeria tenella in chickens

Coccidiosis is a worldwide epidemic intestinal disease with high incidence, which causes huge economic losses. Halofuginone hydrobromide (HF) is widely applied as an effective anticoccidial drug in the poultry industry. However, its therapeutic efficacy is severely restrained due to toxic effects, poor aqueous solubility and low permeability. Nanotechnology can improve the biological effect of drugs, and thus, reduce administered doses and toxic effects. The objective of this study was to investigate the therapeutic and preventive potential of novel HF-loaded D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) polymer micelles (HTPM) for preventing coccidiosis in chickens. The HTPM were approximately spherical with a hydrodynamic diameter of 12.65 ± 0.089 nm, a zeta potential of 8.03 ± 0.242 mV, a drug loading of 14.04 ± 0.12%, and an encapsulation efficiency of 71.1 ± 4.15%. HF was encapsulated in the polymer micelles through interactions with TPGS, as characterized by X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. Cellular take up assays showed that TPGS polymer micelles could enhance drug internalization to alleviate intestinal apoptosis induced by coccidiosis and promote the necrosis of second-generation merozoites of E. tenella. Notably, clinical trials proved that 1.5 mg L^-1 HTPM had a stronger anticoccidial effect on E. tenella than that of 3 mg kg^-1 HF premix. Amplicon sequencing identified that HTPM could alleviate coccidiosis by restoring the structure of the gut microbiome. These findings indicated that the anticoccidial efficacy of HF was significantly enhanced after being encapsulated in polymer micelles, and further demonstrated the potential protective application of nano-encapsulating anticoccidial drugs as a promising approach to control coccidiosis in poultry. In summary, HTPM hold huge potential as an effective therapeutic agent for coccidiosis.