Capsules from pathogenic and non-pathogenic Cryptococcus spp. manifest significant differences in structure and ability to protect against phagocytic cells

Capsule production is common among bacterial species, but relatively rare in eukaryotic microorganisms. Members of the fungal Cryptococcus genus are known to produce capsules, which are major determinants of virulence in the highly pathogenic species Cryptococcus neoformans and Cryptococcus gattii....

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Bibliographic Details
Published in:PloS one 2012-01, Vol.7 (1), p.e29561-e29561
Main Authors: Araujo, Glauber de S, Fonseca, Fernanda L, Pontes, Bruno, Torres, Andre, Cordero, Radames J B, Zancopé-Oliveira, Rosely M, Casadevall, Arturo, Viana, Nathan B, Nimrichter, Leonardo, Rodrigues, Marcio L, Garcia, Eloi S, Souza, Wanderley de, Frases, Susana
Format: Article
Language:English
Subjects:
Acanthamoeba castellanii - cytology
Acanthamoeba castellanii - metabolism
Acanthamoeba castellanii - microbiology
Amoeba
Analysis
Animals
Antibodies
Antibodies, Monoclonal - immunology
Antigens
Antigens, Fungal - immunology
Antimicrobial activity
Bacterial Capsules - chemistry
Bacterial Capsules - immunology
Base Sequence
Biology
Biomphalaria
Capsular polysaccharides
Cell surface
Chemical analysis
Confocal microscopy
Cryptococcus
Cryptococcus - cytology
Cryptococcus - growth & development
Cryptococcus - immunology
Cryptococcus - isolation & purification
Cryptococcus neoformans
Elastic properties
Elasticity
Fungal infections
Fungal Proteins - genetics
Fungal Proteins - metabolism
Fungi
Galactose
Histoplasma capsulatum
Hydrodynamics
Immunology
Kinetics
Light
Macromolecules
Mammals
Mannose
Medicine
Microorganisms
Microscopy
Molecular Sequence Data
Mollusca
Monosaccharides
Monosaccharides - analysis
N-Acetylglucosamine
Oxidative stress
Pathogens
Phagocytes
Phagocytes - cytology
Phagocytes - microbiology
Phagocytosis
Physical properties
Polymerase chain reaction
Polysaccharides
Rigidity
Saccharides
Scattering, Radiation
Sequence Alignment
Snails - microbiology
Species
Studies
Virulence
Viscosity
Xylose
Yeast
Zeta potential
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Summary:Capsule production is common among bacterial species, but relatively rare in eukaryotic microorganisms. Members of the fungal Cryptococcus genus are known to produce capsules, which are major determinants of virulence in the highly pathogenic species Cryptococcus neoformans and Cryptococcus gattii. Although the lack of virulence of many species of the Cryptococcus genus can be explained solely by the lack of mammalian thermotolerance, it is uncertain whether the capsules from these organisms are comparable to those of the pathogenic cryptococci. In this study, we compared the characteristic of the capsule from the non-pathogenic environmental yeast Cryptococcus liquefaciens with that of C. neoformans. Microscopic observations revealed that C. liquefaciens has a capsule visible in India ink preparations that was also efficiently labeled by three antibodies generated to specific C. neoformans capsular antigens. Capsular polysaccharides of C. liquefaciens were incorporated onto the cell surface of acapsular C. neoformans mutant cells. Polysaccharide composition determinations in combination with confocal microscopy revealed that C. liquefaciens capsule consisted of mannose, xylose, glucose, glucuronic acid, galactose and N-acetylglucosamine. Physical chemical analysis of the C. liquefaciens polysaccharides in comparison with C. neoformans samples revealed significant differences in viscosity, elastic properties and macromolecular structure parameters of polysaccharide solutions such as rigidity, effective diameter, zeta potential and molecular mass, which nevertheless appeared to be characteristics of linear polysaccharides that also comprise capsular polysaccharide of C. neoformans. The environmental yeast, however, showed enhanced susceptibility to the antimicrobial activity of the environmental phagocytes, suggesting that the C. liquefaciens capsular components are insufficient in protecting yeast cells against killing by amoeba. These results suggest that capsular structures in pathogenic Cryptococcus species and environmental species share similar features, but also manifest significant difference that could influence their potential to virulence.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0029561