Phaeohyphomycosis

About our research:
     The Szaniszlo Lab's research is primarily in the elucidation of the mechanisms of fungal cell development, specifically that of the fungus, Wangiella dermatitidis (Wd).  Wangiella is used as a model to identify cell-wall virulence factors among dematiaceous (melanized) fungal pathogen of humans.  Specific emphasis is placed on the cell-wall because it is a boundary between host and pathogen, an ultimate determinant of morphology, known to represent a virulence factor, and is a potential target for the design of antifungal drugs.  Particular focus is on the systems leading to chitin localization and melanin enrichments of cell walls in the polarized and nonpolarized vegetative phenotypes known to be expressed by this polymorphic fungus under conditions of human infection.

Thus, the lab's current research is designed to provide insights about how the five chitin synthase (WdCHS) structural genes of Wangiella contribute to its pathogenicity and virulence. The specific aims of the laboratory are

1. To study the WdCHS genes, establish how their expression is regulated, and identify factors that control the time, place and function of their products, with a focus on the mechanisms involved in the very high expression of WdCHS3 and WdCHS5, two genes with no homologs in Saccharomyces cerevisiae or Candida albicans, at 37°C and under other conditions that influence growth, development and differentiation during infections.
2. To establish the individual and collective importance of the five WdChsp isozymes and their chitin products to yeast, isotropic and hyphal growth, and their contributions, if any, to pathogenicity and virulence as augmented by melanin and periods of isotropic enlargement, and with a focus on the potential for WdChs3p and WdChs5p to be particularly vulnerable antifungal targets.
3. To continue to extend the concepts revealed with this model phaeohyphomycotic fungus to a limited number of other dematiaceous pathogens of humans

What is Wangiella dermatitidis?
     Wangiella dermatitidis (aka Exophiala dermatitidis) is a dematiacious fungus known for causing a variety of infections known collectively as "phaeohyphomycosis".   It is a monotypic species in the form-class Deuteromycetes.  What distinguishes it as a dematiacious fungus is the black pigment seen on the walls of its vegetative and reproductive structures -- the hyphae and spores. Wangiella is also a polymorphic organism, taking on a variety of cell types, which include the typical budding yeast cell, isodiametric cell, moniliforme hyphae, true hyphae, and conidia (McIntosh, 1996).  It grows as a yeast in rich liquid medium, but has been shown to convert to other forms by changing growth conditions (de Hoog et al., 1994).

     Phaeohyphomycosis include several human syndromes which include black-grained mycetoma, chromoblastomycosis, tinea nigra, black piedra, keratitis, and onychomycosis.

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