AN ANTIBODY-BASED SCREENING STRATEGY IDENTIFIES SIX C. ALBICANS GENES EXPRESSED DURING HUMAN CANDIDIASIS THAT CONTRIBUTE TO VIRULENCE

Clancy CJ, Cheng S, Nguyen MH

Author address: 

University of Florida College of Medicine and the VA Medical Center, Gainesville, USA

Abstract: 

Our lab is interested in identifying C. albicans genes expressed during human candidiasis as a screening strategy for novel virulence factors. Toward this end, we used sera from HIV-infected patients with oropharyngeal candidiasis (OPC) that had been adsorbed against candidal antigens in vitro to probe a C. albicans genomic expression library. We identified 59 genes encoding immunogenic antigens and confirmed expression within human OPC tissues by RT-PCR and/or immunohistochemistry. Forty-seven in vivo expressed genes have known or putative functions, including transcriptional regulation (16), nutrient metabolism (8), cytoskeleton/cell wall (7), stress response (7), transport (4), and miscellaneous (5). Seven genes encode known C. albicans virulence factors. To prioritize previously unstudied genes for further investigation, we focused on four groups: 1) candidate morphogenesis genes identified by putative function or differential expression; 2) genes encoding proteins homologous to well-established bacterial virulence factors; 3) genes not previously studied in C. albicans that contain recognized functional domains; and 4) genes with no homologues in S. cerevisiae. We used the ura-blaster method followed by reinsertion of URA3 to its native locus to create disruption mutants of representative genes in each group. In group 1, NOT5 and IPF8663 were required for normal morphogenesis in liquid hyphal-inducing media and under microaerophilic conditions of embedded growth, respectively. Both genes were necessary for morphogenesis on solid media, complete virulence during murine disseminated candidiasis (DC) and adherence to oral epithelial cells in vitro. NOT5 made significant contributions to virulence during murine OPC, but could not be implicated during murine vaginal candidiasis or GI colonization and dissemination. Of further note, total immunoglobulin levels against purified Not5p among patients with OPC (10) and DC (11) were significantly higher than levels among healthy controls (11) (p-values
2004

abstract No: 

none

Full conference title: 

14th Annual Focus on Fungal Infections
    • FFI 14th (2004)