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The effects of oxytetracycline on Theileria parva in vitro
1International Laboratory for Research on Animal Diseases, Nairobi, Kenya.
Abstract:
When bovine peripheral blood leucocytes were infected with Theileria parva sporozoites, immediate treatment with oxytetracycline (OTC) inhibited the development of sporozoites to mature schizonts. The extent of inhibition was dependent on drug concentration and duration of treatment. Concentrations of 5 micrograms/ml OTC, or higher, for 8 days completely inhibited the establishment of schizonts and their ability to transform host cells. A cytostatic effect on schizont-infected cell lines was found with three tetracyclines and was also demonstrated on uninfected lymphoblasts. The parasites were found to be sensitive to OTC during development to schizonts, but when mature and established within host cells, schizonts were not demonstrably affected. The infectivity of sporozoites and the binding of sporozoites to lymphocytes were not directly inhibited by OTC. The results may explain the action of tetracyclines when used prophylactically during immunization against East Coast fever, and also the reasons for the ineffectiveness of these drugs when used therapeutically during patent disease.
Insights
Immediate oxytetracycline (OTC) treatment halts Theileria parva development in cattle. This finding explains OTC
Area of Science:
- Veterinary Parasitology
- Molecular Biology
- Pharmacology
Background:
- Theileria parva causes East Coast fever, a significant cattle disease.
- Tetracyclines are sometimes used prophylactically but their therapeutic efficacy is limited.
Purpose of the Study:
- To investigate the effect of oxytetracycline (OTC) on Theileria parva sporozoite development in bovine leukocytes.
- To determine the stage-specific sensitivity of Theileria parva to OTC.
Main Methods:
- Infection of bovine peripheral blood leukocytes with Theileria parva sporozoites.
- Treatment with varying concentrations and durations of oxytetracycline.
- Assessment of schizont development and host cell transformation.
- Cytostatic effect evaluation on infected and uninfected cell lines.
Main Results:
- Immediate OTC treatment inhibited sporozoite development to mature schizonts in a dose- and time-dependent manner.
- Concentrations of 5 µg/ml OTC for 8 days completely prevented schizont establishment.
- OTC exhibited a cytostatic effect on both infected and uninfected lymphoblasts.
- Mature schizonts within host cells were not demonstrably affected by OTC.
Conclusions:
- Oxytetracycline is effective against developing Theileria parva, explaining its prophylactic use.
- OTC's lack of effect on established schizonts explains its therapeutic limitations in treating active East Coast fever.