OVER-EXPRESSION OF SACCHAROMYCES-CEREVISIAE HSP90 ENHANCES THE VIRULENCE OF THIS YEAST IN MICE

Saccharomyces cerevisiae, a yeast of low pathogenic potential, is a ra re but well-documented cause of invasive infections in humans. The yea st Candida albicans is a much commoner cause of significant and life-t hreatening infections. In such infections the heat shack protein hsp90 is an immunodominant antigen associated with protective humoral immun ity. In this study it was shown that over-expression of S. cerevisiae hsp90, the amino acid sequence of which shows 84% identity to C. albic ans hsp90, significantly increased the virulence of a laboratory strai n of S. cerevisiae in mice, both in terms of colony counts in the kidn ey, liver and spleen, and in terms of mortality. This is the first dir ect evidence that hsp90 is a virulence factor.