Experimental murine paracoccidiodomycosis induced by the inhalation of conidia

Abstract

Adult BALB/c mice of both sexes were infected intranasally with 106 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.

The low efficiency of dendritic cells and macrophages from mice susceptible to Paracoccidioides brasiliensis in inducing a Th1 response

“…It is endemic in Latin America and can lead to high mortality rates in the absence of specific therapy or in immunodepressed individuals (1)(2)(3)(4). The infection can be acquired by the respiratory route (5), by inhalation of propagules produced by the fungal mycelial forms that, once in the lungs, undergo differentiation into yeast cells, the infective form of P. brasiliensis. The infection induces the formation of granulomatous lesions primarily in the lungs and then may disseminate to other organs and systems.…”

Evaluation of bronchoalveolar cells in pulmonary paracoccidioidomycosis

“…The disease involves the lungs, mononuclear-phagocytic system and mucocutaneous areas. The infection is caused by inhalation of airborne propagules of the mycelial phase of the fungus, which reach the lungs, eventually evade the host defences and disseminate via the bloodstream and/or lymphatics to virtually all parts of the body [1,2]. The mycosis occurs more frequently in males (80%), most of them farm workers.…”

Análisis de la cinética de expresión de genes durante la transición de micelio a levadura y la germinación levadura a micelio en Paracoccidioides brasiliensis

“…Conidia and mycelial fragments are considered the infectious particles. Once inhaled, they reach the alveoli where at the host's tissues temperature (37 °C) change from its saprophytic form to the parasitic multiple budding yeast form capable of producing disease (8). On the same way, the germination process from the yeast to the mycelium form is an important process during P. brasiliensis life cycle since this allows the fungus to grow under different environmental conditions allowing its return to the natural habitat to re-acquire in this way, its infectious capacity (9).…”