Over-expression of Saccharomyces cerevisiae hsp90 enhances the virulence of this yeast in mice.

Saccharomyces cerevisiae, a yeast of low pathogenic potential, is a rare but well-documented cause of invasive infections in humans. The yeast Candida albicans is a much commoner cause of significant and life-threatening infections. In such infections the heat shock protein hsp90 is an immunodominant antigen associated with protective humoral immunity. In this study it was shown that over-expression of S. cerevisiae hsp90, the amino acid sequence of which shows 84% identity to C. albicans hsp90, significantly increased the virulence of a laboratory strain of S. cerevisiae in mice, both in terms of colony counts in the kidney, liver, and spleen, and in terms of mortality. This is the first direct evidence that hsp90 is a virulence factor.