Experimental paracoccidioidomycosis in mice.

Area of Science:

• Mycology
• Immunology
• Infectious Diseases

Background:

• Paracoccidioides brasiliensis is a fungus causing paracoccidioidomycosis.
• Corticosteroids can modulate host immune responses to fungal infections.
• Understanding the interplay between fungal virulence factors and host immunity is crucial for disease management.

Purpose of the Study:

• To evaluate the virulence and infectivity of nine Paracoccidioides brasiliensis strains in a murine model.
• To assess the impact of corticosteroid treatment on the course of experimental paracoccidioidomycosis.
• To investigate the influence of inoculation route (intranasal vs. intravenous) on disease manifestation.

Main Methods:

• Nine strains of Paracoccidioides brasiliensis were used to inoculate mice intranasally or intravenously.
• Experimental groups included untreated mice and mice treated with corticosteroids.
• Mortality, infection incidence, lesion development, and organ involvement were monitored.

Main Results:

• Corticosteroid administration significantly increased mortality in infected mice, irrespective of the inoculation route.
• Intravenous inoculation generally resulted in higher virulence, except for one strain under corticosteroid influence which was more virulent intranasally.
• Acute lesions were primarily pulmonary; chronic lesions varied in extent and extrapulmonary involvement depending on the inoculation route and corticosteroid treatment.

Conclusions:

• Corticosteroids exacerbate experimental Paracoccidioides brasiliensis infections, increasing mortality and lesion severity.
• The route of inoculation and corticosteroid use significantly influence the virulence and dissemination patterns of Paracoccidioides brasiliensis.
• Further research is needed to elucidate the mechanisms behind corticosteroid-induced immunosuppression in paracoccidioidomycosis.