Phenotypic Characteristics Associated with Virulence of Clinical Isolates from theSporothrixComplex

Abstract

TheSporothrixcomplex members cause sporotrichosis, a subcutaneous mycosis with a wide spectrum of clinical manifestations. Several specific phenotypic characteristics are associated with virulence in many fungi, but studies in this field involving theSporothrixcomplex species are scarce. Melanization, thermotolerance, and production of proteases, catalase, and urease were investigated in 61S. brasiliensis, oneS. globosa, and 10S. schenckiistrains. TheS. brasiliensisstrains showed a higher expression of melanin and urease compared withS. schenckii. These two species, however, presented similar thermotolerances. OurS. globosastrain had low expression of all studied virulence factors. The relationship between these phenotypes and clinical aspects of sporotrichosis was also evaluated. Strains isolated from patients with spontaneous regression of infection were heavily melanized and produced high urease levels. Melanin was also related to dissemination of internal organs and protease production was associated with HIV-coinfection. A murine sporotrichosis model showed that aS. brasiliensisstrain with high expression of virulence factors was able to disseminate and yield a high fungal burden in comparison with a controlS. schenckiistrain. Our results show that virulence-related phenotypes are variably expressed within theSporothrixcomplex species and might be involved in clinical aspects of sporotrichosis.