Candida albicans is an opportunistic dimorphic fungus capable of causing devastating disease in humans. Recent observations have suggested that the surface topography of the cell is dynamic rather than static and variable expression of surface components may occur not just on cells grown under different conditions but on single cells during their lifetime. Such dynamics reflect on mechanisms of synthesis of the cell wall components and their assembly into a functional structure and suggest an additional hierarchy of regulation. They also impact on the commensal and pathogenic relationship of the organism and the host as the organism colonizes the normal host and escapes normal defenses to establish infection in the compromised host. This proposal focuses on the mannoproteins which are the least studied of the wall constituents and have potential for greatest sequence diversity. Mannoprotein has been shown to be at the surface of the cell and both mannan and protein have been implicated in adherence of the fungus to tissue. The research will take the approach of producing monoclonal antibodies to both car bohydrate and protein portions of mannoproteins to identify surface components. The reactivity of these antibodies will be determined with whole cells using indirect immunofluorescence. The nature and identity of the antigenic determinant will be examined using immunoblotting techniques, sensitivity of the antigen to various reagents and other techniques. The extent of epitope expression by growing and stationary phase yeasts cultivated at 28 degrees C and 37 degrees C and germ tubes cultivated at 37 degrees C will be determined. The patterns of expression, kinetics of changes in expression and nature of the determinant will be examined for patterns to develop hypotheses for the regulation of expression and the mechanisms by which such changes are effected. The ability of antibodies to react with surface components will be exploited in studying host-parasite interactions in adherence of fungi to human epithelial cells. Such antibodies will be utilized to select for mutants altered in expression of surface epitopes and these mutants characterized for surface expression and tissue adherence.
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