Paracoccidioides brasiliensis isolated from armadillos is virulent to Syrian hamsters

Isolates of Paracoccidioides brasiliensis may vary in virulence according t o time of in vitro subcultivation. The present study compared the morpholog y and pathogenicity to hamsters of two P. brasiliensis isolates: one obtain ed from human lesions and maintained in the laboratory for several years (P b-18) and the other isolate recovered from hamsters inoculated with organ h omogenates from armadillos (Pb-T). The microscopic morphology of Pb-18 and Pb-T showed yeast cells with similar diameter. However, Pb-T produced a sig nificantly higher number of buds per mother cell than Pb-18. Besides, the m ycelial form of Pb-T developed abundant sporulation during 8 weeks of cultu re which was absent in the Pb-18 isolate. Virulence studies demonstrated th at mortality rates, antibody levels, fungal load and extent of lesions in t he organs were significantly higher in animals infected with Pb-T. The resu lts demonstrated that Pb-T recently isolated from an animal was more virule nt than Pb-18. These differences between the two P. brasillensis isolates m ay be indicators of virulence attenuation in this fungal species.