Cell surface hydrophobicity (CSH) may be a virulence factor for the pathogenic yeast Candida albicans. It contributes to yeast adherence to surfaces, avoidance of phagocytic killing, and yeast to hyphal transition which is considered an important step in dissemination. Little is known about the cell wall components responsible for CSH, thus making useful studies concerning how CSH contributes to pathogenesis of candidiasis, a sometimes fatal disease in immunocompromised patients, not possible. The long-term goal of this proposal is to elucidate how and when CSH is expressed in vivo. Recent unpublished evidence demonstrates that CSH of C. albicans is due to protein. Of particular interest are whether CSH is due to a single or to multiple protein species and whether similar hydrophobic protein(s) is distributed among the different forms of C. albicans which are present in candidal lesions (yeast cells, pseudohyphae, yeast to hyphal transitional cells, and hyphae). Other evidence suggests that hydrophobic proteins may be variably glycosylated, depending on the hydrophobic status of the cell. Whether this is correct and whether glycosylation is somehow otherwise involved in CSH expression must be determined.
One specific aim of this proposal is to isolate and characterize at least one surface hydrophobic protein responsible for CSH of yeast cells. This will be accomplished by a combination of conventional biochemical techniques and immunologic methods. Using these two approaches has the advantage of providing a self-checking system by which only surface hydrophobic protein and cognate antibodies are obtained. The conventional biochemical methods include chromatography and electrophoresis. Hydrophobic interaction chromatography-high performance liquid chromatography and surface radioiodination techniques will also be used to isolate the protein(s) and confirm their surface hydrophobic status. With the development of antibodies to hydrophobic proteins, the question of whether glycosylation influences CSH and whether a hydrophobic protein is ubiquitous among the different forms of C. albicans can be addressed. For the latter, Western blots of cell wall proteins previously separated by electrophoresis will be probed with the antibody. Cross reactive proteins will be immunoprecipitated and compared for molecular weight and other characteristics to the protein isolated from yeast cells. The information obtained through the experiments described in this proposal is expected to serve as a solid foundation for subsequent studies concerning expression in vivo of CSH during development of candidiasis.
