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AN ATTENUATED SURRA OF MAURITIUS WITH IMMUNITY TESTS AFTER RECOVERY
1Laboratories of the Rockefeller Institute for Medical Research, New York.
Abstract:
Apparently as a result of repeated passages through guinea pigs, the virulence of surra of Mauritius for mice became greatly attenuated. Three mice recovered spontaneously and two remained carriers of tryanosomes for four to seven weeks after the parasites were last seen in their blood. The mice that recovered acquired no lasting immunity. While the virulence of the parasites decreased for mice, it increased for guinea pigs. By cultivating the parasites in mice the virulence for these animals was restored after four to eight passages.
Insights
Repeatedly passing surra parasites through guinea pigs attenuated their virulence in mice. However, mouse virulence was restored through serial mouse passages, indicating host-specific adaptation.
Area of Science:
- Parasitology
- Veterinary Medicine
- Immunology
Background:
- Surra, caused by Trypanosoma brucei, is a significant disease in livestock.
- Understanding parasite virulence and host adaptation is crucial for disease control.
Purpose of the Study:
- To investigate the effect of host passage on the virulence of Trypanosoma brucei (surra).
- To assess the development of immunity in mice following attenuated infection.
Main Methods:
- Attenuating Trypanosoma brucei by repeated passages in guinea pigs.
- Infecting mice with attenuated parasites and monitoring parasitemia and recovery.
- Attempting to restore virulence in mice through serial passages in mouse hosts.
Main Results:
- Parasite virulence significantly decreased in mice after guinea pig passages.
- Some mice recovered spontaneously, with two becoming carriers for 4-7 weeks.
- Recovered mice did not develop lasting immunity.
- Parasite virulence increased in guinea pigs.
- Virulence in mice was restored after 4-8 serial passages in mice.
Conclusions:
- Host adaptation plays a critical role in Trypanosoma brucei virulence.
- Attenuated surra parasites can persist as carriers in mice without inducing immunity.
- Serial passage in a specific host can restore parasite virulence for that host.
