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[Activation of the latent Toxoplasma infection and cyst formation in mice]
Abstract:
Latent Toxoplasma infection in mice inoculated with the low virulent Beverley strain (BEV) and avirulent Fukaya strain (FUK) was reactivated by prednisolone administration. Parasitaemia reappeared and the organism could be continuously isolated from the lymph nodes by mouse passage. No distinct decrease in specific antibody levels was observed when the sera were assayed by dye test and latex agglutination test. A significant increase in the number of brain cysts in infected mice was noted at the third week of infection while the challenge infection and steroid immunosuppression treatment resulted in an enhancement of cyst formation. A hypothesis was, therefore, proposed that the cyst formation in tissues might be regulated by the immune response of infected host to Toxoplasma infection.
Insights
Latent Toxoplasma infections in mice were reactivated by prednisolone, leading to parasite resurgence. This suggests host immune responses may regulate Toxoplasma cyst formation in tissues.
Area of Science:
- Immunology
- Infectious Diseases
- Parasitology
Context:
- Latent Toxoplasma gondii infections can persist in hosts.
- Prednisolone can suppress the immune system, potentially reactivating latent infections.
- Understanding parasite-host interactions is crucial for managing toxoplasmosis.
Purpose:
- To investigate the reactivation of latent Toxoplasma infection using different strains (Beverley and Fukaya) in mice.
- To examine the effect of steroid immunosuppression on parasite load and cyst formation.
- To explore the role of the host immune response in regulating Toxoplasma cyst development.
Summary:
- Prednisolone administration reactivated latent Toxoplasma infections in mice, evidenced by reappearing parasitemia and isolation from lymph nodes.
- Specific antibody levels remained largely unchanged, but brain cyst numbers increased significantly, especially with challenge infection and immunosuppression.
- This led to the hypothesis that host immune responses regulate Toxoplasma cyst formation in tissues.
Impact:
- Provides insights into the mechanisms of latent parasitic infection reactivation.
- Highlights the complex interplay between immunosuppression, parasite burden, and cystogenesis.
- Suggests potential targets for therapeutic interventions against chronic toxoplasmosis.