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[Pathogenicity of Acanthamoeba isolated from water]
Abstract:
Two Acanthamoeba strains were isolated from rivers in Berlin by intranasal inoculation into mice. No clinical or pathological symptoms could be observed in the animals. The intention of this study was to initiate and to increase the pathogenicity of these amoebae. The two strains were passaged in mice as well as in liquid medium followed by inoculation into mice. The pathogenicity was measured by the rate of lethality. The first cases of death were found after the 10th passage in those mice which had been infected with the amoebae only passaged in animals. Acanthamoebae could be isolated from brains and lungs, but pathological changes were found only in lungs. After the 11th and 12th animal passage, respectively, the amoebae were only cultivated in vitro for 15 weeks followed by another series of animal passages. Here, first cases of death were recorded after the 5th and 3rd inoculation into mice, respectively. No animals died having been infected with amoebae only maintained in vitro. A third experiment with animal passaged strains showed that mice died even up to the 6th week p.i. and that amoebae could be re-isolated until the 7th week i.p. The results are discussed in view of a possible selection of pathogenic Acanthamoeba strains by fast passages from man to man.
Insights
Pathogenicity of Acanthamoeba strains increased with repeated animal passages, leading to mouse mortality. In vitro cultivation reduced pathogenicity, suggesting animal passage selects for more virulent strains.
Area of Science:
- Microbiology
- Parasitology
- Pathogen Evolution
Context:
- Acanthamoeba species are ubiquitous protozoa found in various environments.
- Some Acanthamoeba strains can cause severe infections in humans, such as keratitis and granulomatous amoebic encephalitis.
- Understanding factors influencing Acanthamoeba pathogenicity is crucial for disease prevention.
Purpose:
- To investigate the potential for increasing the pathogenicity of environmental Acanthamoeba strains.
- To evaluate the role of host passage (in vivo) versus in vitro cultivation on Acanthamoeba virulence.
- To explore the mechanisms underlying Acanthamoeba pathogenicity.
Summary:
- Two environmental Acanthamoeba strains were subjected to serial passages in mice and liquid medium.
- Increased pathogenicity, indicated by a higher mortality rate in mice, was observed after repeated animal passages.
- Acanthamoebae passaged solely in vitro lost pathogenicity, while those passaged in animals demonstrated increased virulence, with mortality observed after fewer passages.
Impact:
- This study suggests that host-to-host transmission could select for more pathogenic Acanthamoeba strains.
- Findings have implications for understanding the emergence and spread of Acanthamoeba infections.
- Highlights the importance of host-animal interactions in pathogen adaptation and virulence.