Pathogenicity of basidiospores ofFilobasidiella neoformansvar.neoformans

Abstract

Basidiospores of Filobasidiella neoformans var. neoformans (progeny of Cryptococcus neoformans MT 100.1 x VR 45980) were able to induce cryptococcosis in Swiss albino mice if inoculated by intraperitoneal injection, nasal instillation or nasal spraying. The latter method, with the aid of a jet nebulizer, was first adopted to imitate the natural entrance of infectious particles. Using this method the small number of basidiospores (7 x 10(3)) could induce cryptococcosis in mice, while the higher number of the parental laboratory-grown yeast cells (1.5 x 10(6)) did not produce infections. By nasal instillation Cyclophosphamide (Cy)-treated mice were more susceptible to the basidiospores, showing 80% cryptococcosis (eight of 10). Seven of the eight infected mice had disseminated cryptococcosis. Immunocompetent mice were more resistant to basidiospore infection than Cy-treated mice, as 40% of that group developed only pulmonary cryptococcosis; none had disseminated infection. Thus, we propose that basidiospores are one form of the infectious propagules of F. neoformans var. neoformans which can cause cryptococcosis, particularly in immunocompromised people.

Global Analyses of Multi-Locus Sequence Typing Data Reveal Geographic Differentiation, Hybridization, and Recombination in the Cryptococcus gattii Species Complex

“…The proliferation of C. gattii in the temperate region as well as an increase in human populations have generated several hypotheses about its emergence and mechanism of dispersal. Surveys of air samples have found particles indictive of C. gattii spores [ 23 ], likely explaining its increasingly broad dispersals and high virulence, as spores are known to be more infectious than yeast cells [ 24 ]. In addition, basidiospores are produced from sexual reproduction, suggesting high levels of fertility among Vancouver Island isolates [ 25 , 26 ].…”

Methods for Manipulating Cryptococcus Spores

“…With the isolation of large numbers of pure spores, the reliable and well-tested murine models of cryptococcal disease could be used to test the capacity of spores to cause disease and determine the nature of spore-mediated infections. As was seen in Galleria and zebrafish larvae, Cryptococcus spores from numerous species and strains, including BT63a x H99α, B3502 x B3501, JEC20 x JEC21, and KN99a x KN99α, have been shown to cause disease in murine models via tail vein injection with disease properties largely indistinguishable from yeast [12,19,30,31].…”

A Velvet Transcription Factor Specifically Activates Mating through a Novel Mating-Responsive Protein in the Human Fungal Pathogen Cryptococcus deneoformans

“…In C. deneoformans , sexual reproduction is thought to facilitate its infection through multiple routes ( 27 , 30 , 32 , 59 – 62 ). In addition to its involvement in pathogenicity, sexual reproduction also enhances the flexibility and resilience of C. deneoformans in competitive environmental niches ( 1 , 7 , 9 , 19 , 60 , 63 , 64 ).…”

“…For instance, sex-created genetic diversity and ploidy variation can facilitate the emergence of hypervirulent or drug-resistant progenies ( 1 , 7 , 9 , 19 , 27 ). In addition, sexual reproduction offers an exclusive route to the production of infectious spores (basidiospores), since asexual sporulation does not occur in this species ( 28 – 32 ). Given the significance of sexual reproduction in C. deneoformans , the underlying genetic basis has been extensively investigated, and multiple signaling pathways and genes involved in sexual reproduction have been explored ( 6 – 8 , 19 , 33 – 35 ).…”