Multilocus microsatellite typing for Cryptococcus neoformans var. grubii

Fifteen randomly selected microsatellites (simple sequence repeats; SSRs), from the H99 Cryptococcus neoformans var. grubii (serotype A) genome, were sequenced, characterized and applied to sequence 87 clinical and environmental C. neoformans var. grubii isolates from 12 different countries based on Multilocus Microsatellite Typing (MLMT). Among the 15 SSR loci, three (designated CNG1, CNG2 and CNG3) were polymorphic, while the remaining 12 SSR loci showed no variations. The specific PCR primers of the polymorphic microsatellites, i.e., CNG1, CNG2 and CNG3, amplified those loci only from strains of C. neoformans (C. neoformans var. grubii, C. neoformans var. neoformans and the AD hybrid) but not from Cryptococcus gattii, suggesting a species-specific association. The three polymorphic microsatellites are useful markers for strain genotyping, population genetic analysis, epidemiological studies, and may be helpful for the diagnosis of cryptococcosis due to C. neoformans.