| Title: | Origin of Cryptococcus neoformans var. neoformans diploid strains |
| Author(s): | Cogliati M; Esposto MC; Clarke DL; Wickes BL; Viviani MA; |
| Address: | "Laboratorio di Micologia Medica, Istituto di Igiene e Medicina Preventiva, Universita degli Studi, IRCCS Ospedale Maggiore, 20122 Milan, Italy" |
| DOI: | 10.1128/JCM.39.11.3889-3894.2001 |
| ISSN/ISBN: | 0095-1137 (Print) 1098-660X (Electronic) 0095-1137 (Linking) |
| Abstract: | "The basidiomycetous yeast Cryptococcus neoformans is an important human fungal pathogen. Two varieties, C. neoformans var. neoformans and C. neoformans var. gattii, have been identified. Both are heterothallic with two mating types, MATa and MATalpha. Some rare isolates are self-fertile and are considered occasional diploid or aneuploid strains. In the present study, 133 isolates, mostly from Italian patients, were investigated to detect the presence of diploid strains in the Igiene Universita Milano culture collection. All of the diploid isolates were further investigated by different methods to elucidate their origins. Forty-nine diploid strains were identified by flow cytometry. PCR fingerprinting using the (GACA)(4) primer showed that the diploid state was associated with two specific genotypes identified as VN3 and VN4. Determination of mating type on V8 juice medium confirmed that the majority of the strains were sterile. PCR and dot blotting using the two pheromone genes (MFa and MFalpha) as probes identified 36 of the 49 diploid isolates as MATa/alpha. The results of pheromone gene sequencing showed that two allelic MFalpha genes exist and are distinct for serotypes A and D. In contrast, the MFa gene sequence was conserved in both serotype alleles. Amplification of serotype-specific STE20 alleles demonstrated that the diploid strains contained one mating locus inherited from a serotype A parent and one inherited from a serotype D parent. The present results suggest that diploid isolates may be common among the C. neoformans population and that in Italy and other European countries serotype A and D populations are not genetically isolated but are able to recombine by sexual reproduction" |
| Keywords: | Cryptococcosis/microbiology Cryptococcus neoformans/*classification/*genetics/physiology Culture Media DNA Fingerprinting/methods *Diploidy Flow Cytometry/methods Haploidy Humans Molecular Sequence Data Pheromones/genetics Polymerase Chain Reaction Sequen; |
| Notes: | "MedlineCogliati, M Esposto, M C Clarke, D L Wickes, B L Viviani, M A eng WT_/Wellcome Trust/United Kingdom R29 AI043522/AI/NIAID NIH HHS/ R29AI43522/AI/NIAID NIH HHS/ Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, P.H.S. 2001/10/30 J Clin Microbiol. 2001 Nov; 39(11):3889-94. doi: 10.1128/JCM.39.11.3889-3894.2001" |
