Effect of Acetamizuril on enolase in second-generation merozoites of Eimeria tenella

•First time, demonstrate a novel anti-coccidiosis triazine compound acetamizuril, could downregulate the protein expression of enolase in the second-generation merozoites.•Found that enolase at the apical end of mz-En, this indicates that enolase may participate in the invasion process of parasites.•Our results indicate that the expression of enolase in different parasitic stages may vary.

As an obligate intracellular apicomplexan parasite, Eimeria tenella (E. tenella) can rapidly invade chicken cecum epithelial cells and cause avian coccidiosis. Enolase, an essential enzyme that catalyzes the reversible conversion of 2-phosphoglycerate into phosphoenolpyruvate, plays a very important role in glycolysis. In this study, each chicken was inoculated with 8 × 104 sporulated E. tenella oocysts suspended in 1 ml of distilled water to determine the effects of acetamizuril, a new triazine anticoccidial drug, on enolase in the second-generation merozoites of E. tenella. The chickens were divided into two groups: the untreatment group (challenged with E. tenella oocysts and provided with normal feed) and the treatment group (challenged with E. tenella oocysts and provided with 5 mg/kg of acetamizuril by oral gavage at 96 h after inoculation). The second-generation merozoites of E. tenella (mz-En) were obtained at 120 h after inoculation. Subsequently, quantitative real-time PCR and Western blotting were conducted to detect the enolase changes in mz-En at the transcriptional and translational levels. The results showed that enolase mRNA expression was downregulated, and the translational level was decreased in the treatment group. In addition, the subcellular localization of enolase demonstrated that enolase was distributed primarily at the top of the mz-En and that the fluorescence intensity was weak after treatment with acetamizuril. These findings indicated that enolase may be a promising target to prevent coccidiosis.