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Special Focus on Endemic Mycoses

The capsule of Cryptococcus neoformans

ORCID Icon, ORCID Icon, , , , & show all
Pages 822-831 | Received 09 Oct 2017, Accepted 16 Jan 2018, Published online: 01 Aug 2018
 

ABSTRACT

The capsule of Cryptococcus neoformans is its dominant virulence factor and plays a key role in the biology of this fungus. In this essay, we focus on the capsule as a cellular structure and note the limitations inherent in the current methodologies available for its study. Given that no single method can provide the structure of the capsule, our notions of what is the cryptococcal capsule must be arrived at by synthesizing information gathered from very different methodological approaches including microscopy, polysaccharide chemistry and physical chemistry of macromolecules. The emerging picture is one of a carefully regulated dynamic structure that is constantly rearranged as a response to environmental stimulation and cellular replication. In the environment, the capsule protects the fungus against desiccation and phagocytic predators. In animal hosts the capsule functions in both offensive and defensive modes, such that it interferes with immune responses while providing the fungal cell with a defensive shield that is both antiphagocytic and capable of absorbing microbicidal oxidative bursts from phagocytic cells. Finally, we delineate a set of unsolved problems in the cryptococcal capsule field that could provide fertile ground for future investigations.

Disclosure of potential conflicts of interest

No potential conflicts of interest were disclosed.

Acknowledgments

A.C. was supported in part by grants 5R01HL059842, 5R01AI033774, 5R37AI033142, and 5R01AI052733.

Additional information

Funding

This work was supported by the HHS | National Heart, Lung, and Blood Institute (NHLBI), R01HL059842; HHS | NIH | National Institute of Allergy and Infectious Diseases (NIAID), R37AI033142; HHS | NIH | National Institute of Allergy and Infectious Diseases (NIAID), R01AI052733; HHS | NIH National Institute of Allergy and Infectious Diseases, AI033774 HHS | NIH | National Institute of Allergy and Infectious Diseases (NIAID) T32AI007417.