Hybrid genotypes in the pathogenic yeast Cryptococcus neoformans

Amplified fragment length polymorphism (AFLP) genotyping of isolates of the pathogenic fungus Cryptococcus neoformans suggested a considerable genetic divergence between the Varieties C. neoformans var. neoformans and C. neof ormans var, grubii on the one hand versus C. neoformans var. gattii on the other. This divergence is supported by additional phenotypic, biochemical, clinical and molecular differences. Therefore, the authors propose the exis tence of two species, C. neoformans (Sanfelice) Vuillemin and C. bacillispo rus Kwon-Chung, which differ in geographical distribution, serotypes and ec ological origin. Within each species three AFLP genotypes occur, which diff er in geographical distribution and serotypes. Differences in ecological or igin (AIDS patients, non-AIDS patients, animals or the environment) were fo und to be statistically not significant. In C. neoformans as well as in C. bacillisporus one of the genotypes represented a hybrid. The occurrence of hybridization has consequences for the reproductive biology of the species, as new genotypes with altered virulence or susceptibility to antifungal dr ugs may arise through the exchange of genetic material.