Chapter 48 : Pathogenicity of Cryptococcus neoformans: an Evolutionary Perspective

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Cryptococcus neoformans has several well-established virulence factors: a polysaccharide capsule that surrounds the cell body, melanin production, urease, phospholypase, and growth at 37°C. Among these factors, the best characterized are the capsule and melanin. The fact that the size of the capsule increases after infection suggests that it is required for survival in the host, and mutants unable to undergo this process are less virulent. The ability of C. neoformans to grow at 37°C and in slightly alkaline pH, which are conditions that the yeast encounters during infection in mammalian hosts, is a main feature that allows this yeast to be a pathogenic fungus. Furthermore, the interaction of C. neoformans with some of other hosts such as bacteria, protozoa and slime molds can enhance virulence by affecting what we consider to be the virulence factors of this yeast and the ability to kill mice. This chapter reviews the interactions and discusses how they may influence the virulence of the organism during evolution. Other virulence factors, such as phospholipase, are important for survival of the yeast cells. The chapter reviews how C. neoformans can infect and interact with many different hosts, including amoebas, nematodes, insects, and many mammals. At the same time, C. neoformans increased virulence by exploiting some of the features that this fungus uses for survival in the environment, such as the capsule and melanin production.

Citation: Zaragoza O, Frasés S, Casadevall A. 2008. Pathogenicity of Cryptococcus neoformans: an Evolutionary Perspective, p 602-590. In Baquero F, Nombela C, Cassell G, Gutiérrez-Fuentes J (ed), Evolutionary Biology of Bacterial and Fungal Pathogens. ASM Press, Washington, DC. doi: 10.1128/9781555815639.ch48
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