Virulence profile of strains of Cryptococcus neoformans var. grubii evaluated by experimental infection in BALB/c mice and correlation with exoenzyme activity
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Eriques Gonçalves da Silva1, Francisco de Assis Baroni2, Flavio César Viani1
1Instituto Ciências Biomédicas, Departamento de Microbiologia, Seção de Micologia, Laboratório de Leveduras Patogênicas, Universidade de São Paulo, Av. Professor Lineu Prestes, 1374, Cidade Universitária, CEP 05508-900, São Paulo, Brazil.
Abstract:
To evaluate the virulence profile of strains of Cryptococcus neoformans var. grubii, 62 strains of this yeast were inoculated into BALB/c mice. It was found that 69 % of the strains were significantly more lethal to the mice and were recovered from a higher percentage (60 %) of the organs compared with the other 31 % of the strains, which were recovered from 35 % of organs tested. Those strains that provoked higher death rates were also recovered from the central nervous system at a higher rate (84 %) than the less lethal strains (32 %). This finding led to an investigation of the factors that enhanced the capacity for neurological infection and death of the animals. The results of this study suggested that environmental strains present different degrees of virulence. The correlation of exoenzyme production before and after inoculation and between the groups of mice indicated that exoenzyme production had no influence on differences in virulence among the strains studied.
Insights
Environmental strains of Cryptococcus neoformans var. grubii show varied virulence. More lethal strains were recovered from more organs, including the central nervous system, suggesting distinct infection capabilities.
Area of Science:
- Mycology
- Infectious Diseases
- Pathogen Virulence
Background:
- Cryptococcus neoformans var. grubii is an opportunistic fungal pathogen.
- Understanding strain-specific virulence is crucial for predicting disease severity and outcomes.
Purpose of the Study:
- To evaluate the virulence profiles of different environmental strains of Cryptococcus neoformans var. grubii.
- To identify factors contributing to the varying pathogenicity and organ tropism of these fungal strains.
Main Methods:
- Inoculation of 62 Cryptococcus neoformans var. grubii strains into BALB/c mice.
- Assessment of lethality, organ recovery rates, and central nervous system (CNS) colonization.
- Correlation analysis of exoenzyme production with observed virulence differences.
Main Results:
- 69% of strains exhibited significantly higher lethality and were recovered from more organs (60%) compared to 31% of strains (35% organ recovery).
- Highly lethal strains showed a higher recovery rate from the CNS (84%) versus less lethal strains (32%).
- Exoenzyme production did not correlate with observed differences in virulence among the studied strains.
Conclusions:
- Environmental strains of Cryptococcus neoformans var. grubii possess distinct virulence characteristics.
- Higher lethality and CNS tropism are associated with specific Cryptococcus neoformans var. grubii strains.
- Exoenzyme production is not a determining factor in the differential virulence of these fungal strains.
