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Experimental study of the pathogenicity of aspergilli for mice
Abstract:
The relative virulence was determined for 14 species of aspergilli, by inoculating normal mice intravenously with graded doses of spores. Eleven were found to possess some degree of virulence, whereas three others were avirulent. Members of the Aspergillus flavus group were the only species that consistently killed mice with doses as low as 10(4) viable spores. When the in vivo fate of spores was compared for a virulent and an avirulent strain of Aspergillus, spores of the latter were cleared rapidly from the liver and spleen but grew in the kidneys and brain, producing progressive disease. Mice which inhaled spores did not succumb, but macrophages washed from their lungs contained spores. A relationship of virulence to spore characteristics such as germination time, size, shape, and external markings could not be established. Virulence could not be related to aflatoxin production inasmuch as at least one virulent strain did not produce aflatoxin in vitro.
Insights
This study investigated Aspergillus species virulence in mice. The Aspergillus flavus group showed the highest virulence, while spore characteristics and aflatoxin production did not correlate with virulence.
Area of Science:
- Mycology
- Infectious Diseases
- Immunology
Background:
- Aspergillosis is a serious fungal infection caused by Aspergillus species.
- Understanding the relative virulence of different Aspergillus species is crucial for predicting disease risk and developing targeted treatments.
Purpose of the Study:
- To determine the relative virulence of 14 Aspergillus species in a mouse model.
- To investigate the relationship between spore characteristics, aflatoxin production, and virulence.
- To compare the in vivo fate of virulent and avirulent Aspergillus strains.
Main Methods:
- Intravenous inoculation of normal mice with graded doses of spores from 14 Aspergillus species.
- Comparison of in vivo spore fate for virulent and avirulent strains.
- Assessment of spore characteristics (germination time, size, shape, external markings).
- Evaluation of aflatoxin production in vitro for selected strains.
Main Results:
- Eleven of the 14 Aspergillus species tested exhibited some degree of virulence in mice.
- The Aspergillus flavus group consistently killed mice at low spore doses (10^4).
- Avirulent strains were rapidly cleared from the liver and spleen but grew in the kidneys and brain, causing progressive disease.
- No clear relationship was found between virulence and spore characteristics or aflatoxin production.
Conclusions:
- Significant variation exists in the virulence of Aspergillus species.
- The Aspergillus flavus group poses a substantial risk for invasive aspergillosis.
- Virulence in this model is not directly linked to easily measurable spore characteristics or aflatoxin production, suggesting complex host-pathogen interactions.