1887

Abstract

The ability of the pathogenic fungus to cause disease requires rapid adaptation to changes in the host environment and to an evolving host immune response. The identification of ‘virulence factors’ using characterization of mutant strains has traditionally relied on a common set of phenotypic and biochemical assays (most often performed at 30 °C) and the subsequent correlation with their corresponding virulence in mouse models of disease. Utilizing a panel of isogenic mutants for the multifunctional signal-modulating 14-3-3 protein (Bmh1p), we have found that specific mutations affect a variety of different pathways currently associated with virulence, including those involved with the formation of filaments, as well as interaction with host immune cells. Surprisingly, our studies revealed that deficiencies in many of these pathways do not always correlate with virulence in a mouse model of disseminated infection. Mutations within the binding pocket of Bmh1p that affect the ability of the protein to efficiently bind ligand had varying effects on the results of a number of and assays. The capability, , to filament in embedment conditions, and to filament and form chlamydospores under microaerophilic conditions on cornmeal agar, does not correlate with virulence. It is likely that only a subset of hyphal signalling pathways is actually required for the establishment of infection in the disseminated mouse model. Most importantly, our results suggest that the delayed onset of lag-phase growth at 37 °C, and not at 30 °C, results in an inability of these mutants to rapidly adjust to environmental changes and may be responsible for their increased clearance and reduced virulence. It is critical, therefore, that future studies of putative virulence factors in include careful characterization at physiological temperatures.

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2009-05-01
2019-10-17
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