A Saccharomyces cerevisiae mutant with increased virulence

Robert T. Wheeler, Martin Kupiec, Paula Magnelli, Claudia Abeijon, Gerald R. Fink

Research output: Contribution to journalArticlepeer-review


Saccharomyces cerevisiae, bakers' yeast, is not a pathogen in healthy individuals, but is increasingly isolated from immunocompromised patients. The more frequent isolation of S. cerevisiae clinically raises a number of questions concerning the origin, survival, and virulence of this organism in human hosts. Here we compare the virulence of a human isolate, a strain isolated from decaying fruit, and a common laboratory strain in a mouse infection model. We find that the plant isolate is lethal in mice, whereas the laboratory strain is avirulent. A knockout of the SSD1 gene, which alters the composition and cell wall architecture of the yeast cell surface, causes both the clinical and plant isolates to be more virulent in the mouse model of infection. The hypervirulent ssd1Δ/ssd1Δ yeast strain is a more potent elicitor of proinflammatory cytokines from macrophages in vitro. Our data suggest that the increased virulence of the mutant strains is a consequence of unique surface characteristics that overstimulate the proinflammatory response.

Original languageEnglish
Pages (from-to)2766-2770
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number5
StatePublished - 4 Mar 2003


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