| Avian coccidiosis is one of the serious infectious diseases of poultry caused by different species of genus Eimeria spp. It causes vast economic losses every year. Though some anticoccidial vaccines are available in the market, and their efficacy is controversial. Farmers mainly rely on the prophylactic and therapeutic use of chemicals for the control of avian coccidiosis. Frequent usage of anticoccidialstats, however, has resulted in the development of resistance in the Eimeria species. Furthermore, with the restricts or disabled the use of antibiotics, consumers have shown increasing concern about drug residues in poultry products. There is therefore a pressing need to move from chemotherapy control of coccidiosis to new methods of control free of any chemical tissue residue. In this research, we first investigated the anticoccidial efficacy of artemisinin against coccidiosis induced by E. tenella. And then, the second-generation merozoites of E. tenella were isolated and used to evaluate the potential mechanism of artemisinin. The results will improve the rational use of anticoccidial drugs to reduce or avoid drug resistance and drug residues or other issues provide a reference.1. To investigate the anticoccidial action of artemisinin on E. tenella infection,72broiler chickens were randomly divided into three groups (control group, challenge control group, and artemisinin-treated group). The results showed that compared with the challenge control group, artemisinin significantly decreased bloody feces, OPG and the levels of serum IL-6and TNF-a, while increased the rates of relative weight gain and survival rates, alleviated the pathological changes of caecum although the anticoccidial index was only139.15. All the date indicated that artemisinin is not a perfect and practical coccidialstat when given by oral way, and dosage form and drug delivery route should be further researched.2. To evaluate the potential mechanism of artemisinin action on the second-generation merozoites of E. tenella. At120h after inoculation by oral E. tenella sporulated oocysts, we collected the second generation merozoites of E. tenella from the chicken’s caecum in different groups (challenge control group, and artemisinin-treated group). The results showed that compared with the challenge control group, artemisinin exerted an extremely significant reduction in mitochondrial transmembrane potential by47.42%(P<0.01), and increased the apoptotic rate by61.93%(P<0.01) in second-generation merozoites, respectively. Ultra structural analysis showed that merozoite size was reduced with increased the density of the cytoplasm, chromatin condensation, in addition, heterochromatin was becoming more apparent marginalization. Histochemical analysis suggested that the integrated optical density (IOD) of caspase-3was significantly increased while IOD of bcl-2was significantly decreased by artemisin in infectious caecum. In conclusion, artemisinin not only accelerated the apoptosis of the second generation merozoites of E. tenella, but also accelerated apoptosis of parasitized organization3. Using quantitative PCR analysis the expression of microneme genes (MIC) mRNA in second-generation merozoites of E. tenella and scanning electron microscopy structure of the cecum showed that compared with the challenge control group, the number of second generation merozoites of E. tenella was decreased by25.37%(P<0.05) in artemisinin-treated group. Meanwhile, the expression level of EtMIC1, EtMIC2, EtMIC3, EtMIC4, EtMIC5were decreased by46.59%(P<0.05),36.53%(P<0.05),57.89%(P<0.01),38.09%(P<0.05),54.53%(P<0.01), respectively. The cecal pathological alterations were mitigated by artemisinin treatment. These results suggested that artemisinin may decrease the number of merozoites by inhibiting the expression levels of microneme genes in second-generation merozoites, and then result in alleviating the cecal lesion. |
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