Candida albicans and other opportunistic pathogens have become increasingly important as medical science improves the treatments of other diseases. This dimorphic fungus is an agent of potentially life threatening disease. The organism is a human comensal and infection is generally of endogenous origin. This proposal is directed towards studying an early event in the pathogenesis of disseminated disease: adhesion to host tissues. Fungal adhesins are putative virulence factors. Adherence is a potential target for development of anti-fungal therapy to supplement the limited options currently available. Adherence to the extracellular matrix (ECM) has been implicated in disseminated Candida infection. The proposal focuses on three proteins found in yeast cells and germ tubes that bind to the ECM component entactin. The functional and structural relationships of these proteins will be elucidated. Biochemical, immunological, and molecular techniques will be used to determine the relationship between ligand specificity, localization, and expression of the binding proteins. An ex vivo assay that separates adherence from other parameters of pathogenesis will be used to elucidate the tissue specificity and characteristics of entactin mediated adherence. Murine spleen, lung, kidney, and liver tissue and primate tissue will be examined. These tissues are major targets of disseminated candidiasis. Mutant strains altered in the expression of entactin binding proteins(s) will be constructed using gene disruption and defective subunit approaches as appropriate. Standard techniques will be used to clone and sequence the gene(s) for entactin binding proteins. The cloned sequence(s) will be used in mutant construction. The deficient strains will be characterized for entactin binding and tissue adherence. The role of these adhesive interactions in pathogenesis will be evaluated in an in vivo murine model of adherence.
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