Pathogenicity of basidiospores of Filobasidiella neoformans var. neoformans

Basidiospores of Filobasidiella neoformans var, neoformans (progeny of Cryp tococcus neoformans MT 100.1 x VR 45980) were able to induce cryptococcosis in Swiss albino mice if inoculated by intraperitoneal injection, nasal ins tillation or nasal spraying. The latter method, with the aid of a jet nebul izer, was first adopted to imitate the natural entrance of infectious parti cles. Using this method the small number of basidiospores (7 x 10(3)) could induce cryptococcosis in mice, while the higher number of the parental lab oratory-grown yeast cells (1.5 x 10(6)) did not produce infections. By nasa l instillation Cyclophosphamide (Cy)-treated mice were more susceptible to the basidiospores, showing 80% cryptococcosis (eight of 10). Seven of the e ight infected mice had disseminated cryptococcosis. Immunocompetent mice we re 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 infectio us propagules of F. neoformans var. neoformans which can cause cryptococcos is, particularly in immunocompromised people.