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Published on: December 9, 2014
Toxoplasma gondii: protection against colonization of the brain and muscles in a rat model
1Laboratorio de Toxoplasmosis, Departamento de Parasitología, Universidad de la Republica, Facultad de Veterinaria, Alberto Lasplaces 1550, Montevideo 11600, Uruguay. freyrealvaro@hotmail.com
Abstract:
The objective was to test immune protection against the formation of Toxoplasma gondii tissue cysts in rats. It has been previously shown that 50 T. gondii tissue cysts of strain Me49 are not pathogenic for CF-1 mice, whereas 1 T. gondii tissue cyst of strain M-7741, can be lethal for mice 11-13 days after subcutaneous or oral administration. In the present study, ten rats were fed T. gondii oocysts of strain Me49 and after a further 30 days they were each orally challenged with T. gondii oocysts of strain M-7741. Thirty days after this, they were euthanased and brain and muscle samples inoculated subcutaneously or orally dosed, respectively, to mice for bioassay. None of the mice died, whereas all the mice that were inoculated with brain homogenates or were fed muscle samples from four non-immunized rats that had been inoculated with T. gondii oocysts of strain M-7741, died. These results encourage further research towards achieving vaccinal protection against the formation of T. gondii tissue cysts in meat animals and people.
Insights
Rats immunized with Toxoplasma gondii strain Me49 oocysts resisted challenge with lethal strain M-7741 oocysts. This suggests potential for vaccinal protection against Toxoplasma gondii tissue cysts in animals and humans.
Area of Science:
- Immunology
- Parasitology
- Veterinary Medicine
Background:
- Toxoplasma gondii tissue cysts can cause severe disease.
- Strain M-7741 is lethal to mice, while strain Me49 is not pathogenic.
- Immune protection against Toxoplasma gondii tissue cyst formation is a significant research goal.
Purpose of the Study:
- To evaluate immune protection against Toxoplasma gondii tissue cyst formation in rats.
- To determine if prior exposure to a non-pathogenic strain confers protection against a lethal strain.
Main Methods:
- Rats were orally administered Toxoplasma gondii oocysts of strain Me49.
- After 30 days, rats were challenged orally with Toxoplasma gondii oocysts of strain M-7741.
- Brain and muscle tissues were used for bioassays in mice to assess cyst presence and viability.
Main Results:
- None of the mice challenged with tissues from immunized rats succumbed to infection.
- Mice challenged with tissues from non-immunized rats infected with strain M-7741 died, confirming its lethality.
- This indicates successful immune protection was established in the rats.
Conclusions:
- Immunization with Toxoplasma gondii strain Me49 oocysts provides protection against subsequent lethal challenge.
- These findings support further investigation into vaccines for preventing Toxoplasma gondii tissue cysts in food animals and humans.
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