A rapid method for determining salinomycin and monensin sensitivity in Eimeria tenella

Area of Science:

• Veterinary Parasitology
• Molecular Biology
• Antimicrobial Resistance

Background:

• Standard Eimeria ionophore sensitivity testing involves in vivo chicken infection, which is time-consuming and resource-intensive.
• Eimeria tenella causes significant economic losses in poultry farming, necessitating efficient methods for monitoring drug resistance.

Purpose of the Study:

• To develop and validate a rapid in vitro assay for determining Eimeria tenella sensitivity to the ionophores salinomycin and monensin.
• To compare the efficacy of molecular methods (qPCR, sqPCR) with traditional sporozoite counting for assessing drug sensitivity.

Main Methods:

• Cultured MDBK cells were infected with E. tenella sporozoites and exposed to varying concentrations of salinomycin or monensin.
• Intracellular sporozoites and DNA were analyzed at 24 hours using direct counting, semi-quantitative PCR (sqPCR), and quantitative PCR (qPCR).
• The assay was validated using E. tenella field isolates known to be resistant to ionophores.

Main Results:

• A dose-dependent decrease in E. tenella sporozoites and DNA was observed with increasing drug concentrations, consistent across all tested methods.
• Quantitative PCR (qPCR) demonstrated higher sensitivity in detecting drug effects compared to sporozoite counting and sqPCR.
• The in vitro assay successfully identified ionophore-resistant E. tenella field isolates, showing higher DNA levels than the sensitive laboratory strain.

Conclusions:

• The developed in vitro assay provides a rapid, cost-effective, and reliable method for assessing Eimeria tenella ionophore sensitivity.
• Molecular techniques, particularly qPCR, enhance the sensitivity and accuracy of in vitro drug resistance testing.
• This assay facilitates timely monitoring of anticoccidial drug resistance in Eimeria, crucial for effective poultry health management.