Diclazuril-Induced Expression of CDK-Related Kinase 2 in the Second-Generation Merozoites of Eimeria Tenella

Abstract Background：Coccidiosis caused by Eimeria tenella infection, directly or indirectly leads to great loss to poultry industry. With the emergence of drug-resistance in chicken coccidia, it is imperative to develop new drugs. Cyclin-dependent kinases (CDKs) regulate cell cycle progression in numerous organisms by acting as key molecular switches. Results: In the present study, a diclazuril anticoccidiosis animal model was established and CDK-related kinase 2 (CRK2) in the second-generation merozoite of E. tenella (EtCRK2) gene was amplified through reverse transcription-polymerase chain reaction (RT-PCR) and expressed in Escherichia coli Rosetta (DE3). Purified recombinant protein was used for antiserum preparation. Subsequently, EtCRK2 transcription and translation levels were detected through quantitative real-time PCR and Western blot analysis, respectively. The localization of EtCRK2 in merozoites was examined via immunofluorescence techniques. Results showed that the 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 localized in the cytoplasm of merozoites. The fluorescence intensity of EtCRK2 in the infected/diclazuril group was significantly weaker than that in the infected/control group. Conclusions: This study demonstrated that the anticoccidial drug diclazuril against E. tenella by affecting the expression pattern of EtCRK2 molecule, and EtCRK2 may be used as a candidate target for new drug development.