Extracellular vesicles produced by Cryptococcus neoformans contain protein components associated with virulence.
Cryptococcus neoformans produces vesicles containing its major virulence factor, the capsular polysaccharide glucuronoxylomannan (GXM). These vesicles cross the cell wall to reach the extracellular space, where the polysaccharide is supposedly used for capsule growth or delivered into host tissues. In the present study, we characterized vesicle morphology and protein composition by a combination of techniques including electron microscopy, proteomics, enzymatic activity, and serological reactivity. Secretory vesicles in C. neoformans appear to be correlated with exosome-like compartments derived from multivesicular bodies. Extracellular vesicles manifested various sizes and morphologies, including electron-lucid membrane bodies and electron-dense vesicles. Seventy-six proteins were identified by proteomic analysis, including several related to virulence and protection against oxidative stress. Biochemical tests indicated laccase and urease activities in vesicles. In addition, different vesicle proteins were recognized by sera from patients with cryptococcosis. These results reveal an efficient and general mechanism of secretion of pathogenesis-related molecules in C. neoformans, suggesting that extracellular vesicles function as "virulence bags" that deliver a concentrated payload of fungal products to host effector cells and tissues.
Instituto de Microbiologia Professor Paulo de Góes, Universidade Federal do Rio de Janeiro, 21941590 Rio de Janeiro, Brazil.
Marcio L
ML
Rodrigues
Ernesto S
ES
Nakayasu
Debora L
DL
Oliveira
Leonardo
L
Nimrichter
Joshua D
JD
Nosanchuk
Igor C
IC
Almeida
Arturo
A
Casadevall
D000946:Antigens, Fungal / Q000378:metabolism; D015153:Blotting, Western; D002473:Cell Wall / Q000378:metabolism; D003453:Cryptococcosis / Q000378:metabolism* / Q000473:pathology; D003455:Cryptococcus neoformans / Q000472:pathogenicity*; D006801:Humans; D042845:Laccase / Q000378:metabolism; D013058:Mass Spectrometry; D040901:Proteomics; D022161:Transport Vesicles / Q000502:physiology* / Q000648:ultrastructure; D014510:Urease / Q000378:metabolism; D014774:Virulence; D037521:Virulence Factors / Q000378:metabolism*
D000946:Antigens, Fungal; D037521:Virulence Factors; D042845:Laccase; D014510:Urease