Pathogenicity of basidiospores of Filobasidiella neoformans var. 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.

Cryptococcosis

“…Even same sex mating between 2 strains of the same type (MATα–MATα) does occur and is thought to produce the infectious spores that cause human infection. 24,25 This nonclassical mating between 2 α–α strains allows for further genetic diversity and is implicated in the production of hypervirulent, clonal strains responsible for the C gattii outbreak on Vancouver Island, suggesting that such mechanisms may confer the yeast the ability to exploit new geographic niches. 26,27 Furthermore, there are locations in Botswana where there are equal proportions of MATα and MATa isolates in both environmental and clinical populations, providing evidence that sexual recombination remains active even with the spread worldwide of relatively clonal strains.…”

Development and validation of benomyl birdseed agar for the isolation of Cryptococcus neoformans and Cryptococcus gattii from environmental samples

“…The most common manifestations of cryptococcosis are meningitis and primary pulmonary infection, but these organisms can also cause both disseminated and cutaneous infections in humans and animals [1]. It is believed that this disease is primarily contracted through the inhalation of aerosolized yeast or basidiospores from the environment [2,3,4]. …”

Light Controls Growth and Development via a Conserved Pathway in the Fungal Kingdom

“…A similar process, known as haploid or monokaryotic fruiting, can occur with only one mating partner that also gives rise to filaments that terminate in basidium-like structures and produce short spore chains. Spores have been implicated as an infectious propagule, further underscoring the importance of understanding the regulatory processes governing basidiospore production [18,19]. Mating and fruiting are controlled in the laboratory by stimuli such as the presence of potential mating partners (via pheromone signaling), nutrient limitation, desiccation, temperature, and light [19].…”