CELL SURFACE DYNAMICS OF MANNOPROTEINS OF C ALBICANS

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DESCRIPTION (adapted from applicant's abstract): Candida albicans is an opportunistic dimorphic fungus capable of causing devastating disease in humans. Recent studies suggest that the surface topography of the cell is dynamic rather than static and that changes occur not just on cells grown under different conditions, but on single cells in the absence of cell division. Such dynamics reflect on mechanisms of synthesis and regulation of cell wall components and their assembly into a functional structure. They also impact on the interactions between the organism and host in health and disease since many of these interactions are mediated at the cell surface. This proposal focuses on the mannoproteins and proteins, which are the least well characterized constituents and have potential for great diversity. These components have been shown as a class to be present at the surface and implicated in the adherence of the fungus to host tissue and binding of host proteins. The research will take the approach of producing monoclonal antibodies to both carbohydrate and protein portions of these components to identify surface moieties. Antibodies will also be produced to constituents associated with binding of host proteins and fungal morphogenesis. The reactivity of these antibodies will be determined with whole cells using indirect immunofluorescence. The nature and identity of the antigenic determinants 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 and germ tubes will be determined. Since the organism is exposed to multiple antibodies and host proteins in the host, the affect of simultaneous binding of these to fungi will be examined in vitro. 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 interaction in adherence of fungi to tissue sections of murine spleen, liver, lymph node, kidney, etc. Tissues from normal, immunocompromised and cytotoxic antineoplastic drug treated animals will be examined to assess the effect of the state of the host on the extent and localization of binding. Antibodies and other proteins binding to the surface will be utilized to select for mutants altered in expression of surface epitopes and these mutants characterized for surface expression and tissue adherence.