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Experimental murine paracoccidiodomycosis induced by the inhalation of conidia
Abstract:
Adult BALB/c mice of both sexes were infected intranasally with 10(6) viable P. brasiliensis conidia. Animals were sacrificed at intervals up to 6 months and studied by histopathology and organ cultures. At the time of challenge lung sections showed that instilled conidia had reached the alveoli; at 12 h such conidia were transforming into yeast cells, with multiple buds appearing by 18 h. Initially, the cellular infiltrate was composed of polymorphonuclear leukocytes; 6 days later, lymphocytes, plasmocytes and macrophages predominated. Multinucleated giant cells appeared only after 6 weeks. The rate of pulmonary infection as determined by organ culture was high (82 of the 83 mice studied). The experimental infection was progressive as indicated by increasing numbers of viable fungi with time. The results of this study demonstrate that the conidia produced by P. brasiliensis mycelial form are infectious, producing active disease in healthy animals.
Insights
Infectious Paracoccidioides brasiliensis conidia cause progressive pulmonary disease in mice. This study details the histopathology and fungal development during experimental infection.
Area of Science:
- Medical Mycology
- Infectious Diseases
- Immunology
Background:
- Paracoccidioides brasiliensis is a fungus causing paracoccidioidomycosis.
- The infectious form of P. brasiliensis is the conidia.
- Understanding the initial host response to conidia is crucial.
Purpose of the Study:
- To investigate the infectivity of P. brasiliensis conidia.
- To characterize the early histopathological changes in a mouse model.
- To determine the progression of experimental pulmonary infection.
Main Methods:
- Intranasal inoculation of BALB/c mice with P. brasiliensis conidia.
- Histopathological examination of lung tissues at various time points.
- Organ culture to quantify fungal burden.
Main Results:
- Conidia successfully infected mouse lungs, transforming into yeast cells within 18 hours.
- Early inflammatory response involved polymorphonuclear leukocytes, followed by lymphocytes, plasmocytes, and macrophages.
- Multinucleated giant cells appeared after 6 weeks; infection was progressive and widespread.
Conclusions:
- P. brasiliensis conidia are infectious and capable of causing active pulmonary disease in healthy animals.
- The study provides insights into the pathogenesis of experimental paracoccidioidomycosis.
- This model is suitable for studying host-pathogen interactions in P. brasiliensis infection.