Virulence Properties and Nonimmune Pathogenetic Mechanisms of Fungi

This article summarizes some of the potential fungal virulence factors, their effect on the host's defense systems, and their regulation by host factors. Immunopathogenesis is not discussed, but the role of adherence by fungal organisms to human surfaces and foreign bodies in pathogenesis is described. Dimorphism and, less commonly, phenotypic switching may play important roles in initiating and establishing infections by several fungi. Toxins, especially exotoxins, do not seem to participate significantly in pathogenesis; however, various enzymes (proteases, phospholipases) may represent virulence properties of Candida, Aspergillus, and a number of other fungi. The interaction of the organisms with their hormonal milieu, the iron-scavenging capacities of various fungi, and their potential role in pathogenesis are delineated. The immunosuppressive effects of certain fungal antigens, such as yeast mannans, are discussed.