Paracoccidioides brasilienses isolates obtained from patients with acute and chronic disease exhibit morphological differences after animal passage

Abstract

SUMMARYThe basis for virulence in Paracoccidioides brasiliensis is not completely understood. There is a consensus that the sequencial in vitro subcultivation of P. brasiliensis leads to loss of its pathogenicity, which can be reverted by reisolation from animal passage. Attention to morphological and biochemical properties that are regained or demonstrated after animal passage may provide new insights into factors related to the pathogenicity and virulence of P. brasiliensis. We evaluated morphological characters: the percentage of budding cells, number of buds by cell and the diameter of 100 mother cells of yeast-like cells of 30 P. brasiliensis isolates, before and after animal passage. The isolates were obtained from patients with different clinical forms of paracoccidioidomycosis (PCM): acute form (group A, n=15) and chronic form (group C, n=15). The measurement of the yeast cell sizes was carried out with the aid of an Olympus CBB microscope coupled with a micrometer disc. We measured the major transverse and longitudinal axes of 100 viable cells of each preparation. The percentage of budding cells as also the number of buds by cell was not influenced by animal passage, regardless of the source of the strain (acute or chronic groups). The size values of P. brasiliensis isolates from groups A and C, measured before the animal passage exhibited the same behavior. After animal passage, there was a statistically significant difference between the cell sizes of P. brasiliensis isolates recovered from testicles inoculated with strains from groups A and C. The maximum diameter of mother cells from group A isolates exhibited a size of 42.1µm in contrast with 32.9µm exhibited by mother cells from group C (p<0.05). The diameter of 1500 mother cells from group A isolates exhibited a medium size of 16.0µm (SD ± 4.0), a value significantly higher than the 14.1µm (SD = ± 3.3) exhibited by 1500 mother cells from group C isolates (p<0.05). Our results reinforce the polymorphism exhibited by P. brasiliensis in biological material and the need for further investigations to elucidate the role of morphological parameters of the fungus in the natural history of the disease.

Molecular Identification, Antifungal Susceptibility Profile, and Biofilm Formation of Clinical and Environmental Rhodotorula Species Isolates

“…It was also observed that the storage time of the samples did not affect the biofilm formation capability of R. mucilaginosa clinical isolates. This finding conflicts with the hypothesis that the expression of virulence factors by fungi may be substantially impaired by long-term storage of strains (34,35). The antifungal susceptibility profiles obtained strongly suggest that the genus Rhodotorula is not a target for FLC or CAS.…”

Decreased expression of 14-3-3 inParacoccidioides brasiliensisconfirms its involvement in fungal pathogenesis

“…These findings support the previous hypothesis, that the most virulent isolate has more buds, but evaluating the contribution of morphological differences to disease progression requires further investigation of the polymorphisms present in P. brasiliensis. 33 Other evidence pointing to the possible involvement of the 14-3-3 protein in P. brasiliensis morphology includes the findings that both the yeast-to-mycelium transition and the reverse transition were hampered in the isolate with reduced expression of this protein. This suggests that Pb14-3-3 is important for pathogenicity that its closely associated with dimorphic transition: P. brasiliensis mycelium of strains that are unable to transform into yeast are not virulent 34,35 because the yeast form is more resistant to the killing mechanisms of various host cells, thereby contributing to the survival of the pathogen in this environment.…”

Cdc42p controls yeast-cell shape and virulence of Paracoccidioides brasiliensis

“…Besides its unique budding pattern and cell division, the yeast form of P. brasiliensis is also characterized by a polymorphic cell growth, i.e., the existence of mother and bud cells during growth with extreme variations in cell size and shape within the same cellular population, suggesting that these cells may follow, if not a different set of rules, at least a lax control of the establishment and maintenance of polarity during growth. Nonetheless, there have been very few studies addressing these issues as relevant factors during infection (Brummer et al, 1990;Kurokawa et al, 2005;Svidzinski et al, 1999;Villar and Restrepo, 1989).…”