Molecular characterization and analysis of enoyl-CoA hydratase/isomerase family protein of Eimeria tenella

Abstract

Avian coccidiosis is an important intestinal disease caused by Eimeria spp., which leads to significant economic losses in the poultry industry. Although anticoccidial drugs can effectively control it in intensive farming, their extensive and irrational use has induced drug resistance in Eimeria species. Our previous RNA-seq study revealed differential expression of the enoyl-CoA hydratase/isomerase family protein (EtECHI) between drug-sensitive (DS) and drug-resistant Eimeria tenella strains. In this study, qPCR analysis showed that EtECHI mRNA levels were significantly upregulated in diclazuril-resistant (DZR) and maduramicin-resistant (MRR) strains compared to the DS strain. Furthermore, EtECHI transcription increased progressively with rising concentrations of MRR and DZR. Additionally, EtECHI transcript levels were significantly higher in field-isolated diclazuril-resistant strains than in the DS strain. qPCR and western blot analyses showed that EtECHI expression levels were highest in E. tenella unsporulated oocysts. Indirect immunofluorescence assays (IFA) revealed that EtECHI was primarily localized in the cytoplasm of the parasite, with additional surface distribution. An in vitro inhibition assay demonstrated that anti-rEtECHI polyclonal antibodies significantly reduced E. tenella sporozoites' invasion of DF-1 cells. These findings suggest that EtECHI may be associated with the drug resistance of E. tenella and may play a role in parasite growth and development within host cells.