Related Experiment Videos
Studies on the stage of action of ionophorous antibiotics against Eimeria
Abstract:
Sporozoites of Eimeria tenella were treated with different anticoccidial drugs in vitro and their subsequent viability was tested by inoculating them into chicken embryos. Monensin, salinomycin, lasalocid, and arprinocid, at concentrations between 0.01 and 1.0 micrograms/ml, greatly reduced sporozoite viability as judged by mortality, hemorrhage and specific lesions in the embryo chorioallantois. Monensin was also effective in reducing the viability of sporozoites of E. mivati and E. tenella as judged by oocyst production occurring in embryos; activity of monensin was greater against E. tenella than against E. mivati. Monensin (0.1 mg) inoculated into embryos inhibited development of E. tenella. Oocysts which were produced in the presence of the drug sporulated normally and sporozoites obtained from them were fully infective. By initiating treatment of chickens with monensin at different times in relation to infection, it was shown that the drug exerts its anticoccidial effect on the primary invasive stage and on the gametogonous stage of E. tenella and E. necatrix. The effect of gametogony was tested by initiating infections with second generation merozoites of E. tenella. Significant reduction in oocyst production occurred in three of four strains of E. tenella tested. Medication with monensin initiated before merozoite inoculation was effective in inhibiting oocyst production, but medication starting 5 hr after merozoite inoculation was not. This differed from the effects of arprinocid and sulfaquinoxaline which were expressed both before and 5 hr after merozoite inoculation. The results show that the ionophorous anticoccidial drugs exert their anticoccidial action primarily against the invasive stages of Eimeria.
Insights
Ionophorous anticoccidial drugs like monensin effectively reduce Eimeria tenella sporozoite viability and inhibit parasite development. These drugs primarily target the invasive and gametogonous stages of Eimeria species in chickens.
Area of Science:
- Veterinary Parasitology
- Poultry Health
- Antiparasitic Drug Discovery
Background:
- Coccidiosis, caused by Eimeria parasites, is a significant disease in poultry.
- Effective control of Eimeria infections relies on anticoccidial drugs.
- Understanding drug mechanisms is crucial for combating resistance.
Purpose of the Study:
- To evaluate the in vitro and in vivo efficacy of anticoccidial drugs against Eimeria tenella.
- To determine the specific life cycle stages targeted by ionophorous anticoccidials.
- To compare the activity of monensin with other anticoccidial agents.
Main Methods:
- In vitro treatment of Eimeria tenella sporozoites with anticoccidial drugs.
- Inoculation of treated sporozoites into chicken embryos to assess viability.
- In vivo administration of monensin to infected chickens at different time points.
- Assessment of oocyst production and parasite development.
Main Results:
- Monensin, salinomycin, lasalocid, and arprinocid significantly reduced sporozoite viability in chicken embryos.
- Monensin demonstrated efficacy against Eimeria mivati and E. tenella, with greater activity against E. tenella.
- Monensin treatment in chickens targeted the primary invasive and gametogonous stages of E. tenella and E. necatrix.
Conclusions:
- Ionophorous anticoccidial drugs primarily act against the invasive stages of Eimeria.
- Monensin's anticoccidial effect is linked to its action on early developmental stages.
- Drug timing is critical for efficacy, particularly against the gametogonous stage.