Presence of a and a Mating Types in Environmental and Clinical Collections of Cryptococcus neoformans var. gattii Strains from Australia (original) (raw)
Related papers
1999
Cryptococcus neoformans var. gattii lives in association with certain species of eucalyptus trees and is a causative agent of cryptococcosis. It exists as two mating types, MAT␣ and MATa, which is determined by a single-locus, two-allele system. In the closely related C. neoformans var. neoformans, the ␣ mating type has been found to outnumber its a counterpart by at least 30:1, but there have been very limited data on the proportions of each mating type in C. neoformans var. gattii. In the present study, specific PCR primers were designed to amplify two separate ␣-mating-type genes from C. neoformans var. gattii strains. These were used to survey for the presence of the two mating types in clinical and environmental collections of C. neoformans var. gattii strains from Australia. Sixty-eight of 69 clinical isolates produced both ␣ mating type-specific bands and were assumed to be of the ␣ mating type. The majority of environmental isolates were also of the ␣ mating type, but the a mating type was located in two separate areas. In one area, the a mating type outnumbered the ␣ mating type by 27:2, but in the second area, the ratio of the two mating types was close to the 50:50 ratio expected for sexual recombination.
Journal of clinical microbiology, 1999
Cryptococcus neoformans var. gattii lives in association with certain species of eucalyptus trees and is a causative agent of cryptococcosis. It exists as two mating types, MATα and MATa, which is determined by a single-locus, two-allele system. In the closely related C. neoformansvar. neoformans, the α mating type has been found to outnumber its a counterpart by at least 30: 1, but there have been very limited data on the proportions of each mating type in C. neoformans var. gattii. In the present study, specific PCR primers ...
Determination of Cryptococcus neoformans var. neoformans mating type by multiplex PCR
Clinical Microbiology and Infection, 2004
Mating type plays an important role in the epidemiology and virulence of Cryptococcus neoformans. The present study designed a multiplex PCR method to distinguish the six mating type patterns (Aa, Da, Aa, Da, Aa ⁄ Da, and Aa ⁄ Da) of C. neoformans var. neoformans. PCR amplification identified one fragment for Aa (860 bp), Da (413 bp) and Da (645 bp) strains, two fragments for Aa (320 and 400 bp) and Aa ⁄ Da (860 and 413 bp) strains, and three fragments (645, 400, 320 bp) for an Aa ⁄ Da strain. The method appears to be a valid, simple and relatively inexpensive tool for epidemiological and virulence studies.
Journal of Clinical Microbiology, 2002
To better understand the epidemiology and population structure of Cryptococcus neoformans , we determined mating types for 358 C. neoformans strains isolated through the active surveillance program from 1992 to 1994 in four geographic areas in the United States: San Francisco, California; Georgia; Texas; and Alabama. Two assays were used to determine mating types: (i) crossing with standard laboratory tester strains JEC20 and JEC21 on V8 agar medium; and (ii) PCR with the mating type α allele-specific primer of the STE12 gene and with serotype (A and D)- and mating type (a and α)-specific primers of the STE20 gene. Using these two methods, we found that this sample consisted of the following: (i) 324 serotype A, mating type ( MAT ) α (Aα) strains; (ii) 12 serotype D, α (Dα) strains; (iii) 14 serotype AD strains with mating type alleles Aa and Dα (AaDα); (iv) 2 serotype AD strains with mating type alleles Aα and Da (AαDa); (v) 3 serotype B, α (Bα) strains; and (vi) 3 serotype AD stra...
Transactions of the Royal Society of Tropical Medicine and Hygiene, 1997
The 2 known host trees of Cryptococcus neoformans var. gattii, Eucalyptus camaldulensis and E. teretiornis, do not occur naturally in the 'Top End' of the Northern Territory (NT) of Australia. Nine clinical isolates of C. neoformans var. gattii from the NT were analysed by random amplification of polymorphic deoxyribonucleic acid (RAPD) and polymerase chain reaction 'fingerprinting'.Two isolates were assigned toRAPD profile VGI, previously established as the common RAPD profile. The remaining 7 were assigned to profile VGII; 6 of these isolates were recovered from individuals living in the 'Top End'.The results strongly support the existence of an alternative environmental niche for C. neoformans var. gattii, as all isolates from Eucalyptus spp. in Australia to date have been of RAPD profileVG1.
Infection and Immunity
Four strains of Cryptococcus neoformans var. gattii originating from Eucalyptus camaldulensis, three from Australia and one from San Francisco, were tested for their serotype, virulence for mice, and a number of genetic and molecular characteristics. All were found to be serotype B and showed significantly higher virulence for mice than did the type strains of C. neoformans var. gattii and Filobasidiella neoformans var. bacilispora, which were obtained from human cryptococcosis cases. Electrophoretic karyotypes of the strains from Australia were identical, although they were collected from sites at least 15 to 500 km apart. The electrophoretic karyotype of the strain from San Francisco was the same as that of the Australian isolates except for the mobility of one chromosome. On the contrary, no two isolates of serotype B (of a total of 11) from clinical sources were the same, regardless of their geographic origin. Furthermore, none of the clinical isolates showed a chromosomal banding pattern identical to that of Eucalyptus-originated strains. The Eucalyptusoriginated strains failed to form dikaryons when crossed with the tester strains of the two varieties of F. neoformans. Hybridization analysis with a nucleic acid probe (AccuProbe C. neoformans Culture Confirmation Test; Gen-Probe Inc., San Diego, Calif.), however, showed signals of equal intensity for clinical strains and the Eucalyptus-originated strains. Various fungi phylogenetically related to C. neoformans, including a phenol oxidase-positive strain of Cryptococcus laurentii obtained from E. camaldulensis, were negative in the nucleic acid hybridization test. These observations confirm that, in spite of karyotypic differences and the lack of dikaryon formation with the tester strains ofF. neoformans, Eucalyptus-originated C. neoformans var. gattii is the same organism as those isolated from cases of human infection. Furthermore, the C. neoformans culture confirmation test using a commercial nucleic acid probe is specific for C. neoformans.
Journal of clinical …, 1996
Sixty-one clinical and forty-nine environmental isolates of Cryptococcus neoformans var. gattii from Australia and the United States were analyzed by random amplification of polymorphic DNA (RAPD), using 12-to 22-mer primers in pairs, and/or PCR fingerprinting with a single primer derived from the microsatellite core sequence of the wild-type phage M13 (5 GAGGGTGGCGGTTCT 3). Three major genetic profiles were identified by both typing techniques. A single RAPD profile (VGI) predominated among clinical isolates (44 of 48, 92%) and isolates from host eucalypts (45 of 45, 100%) from Australia. Of the 94 Australian isolates, 4 (3 clinical and 1 environmental) were assigned to profile VGII; 2 of these were recovered from patients and one was recovered from plant debris from Western Australia. Only one Australian clinical isolate was assigned to profile VGIII. A different distribution of RAPD profiles (four VGIII, two VGII, and one VGI) was found among four clinical and three environmental isolates from the United States. RAPD profiles of 8 of the 101 isolates studied revealed minor genetic variants, 4 of profile VGI and 4 of profile VGII. Genetic concordance between the majority of clinical and environmental isolates in Australia is consistent with the hypothesis that human disease is acquired from exposure to host eucalypts. Profiles of clinical isolates were independent of body site of infection, and profiles of all isolates were stable over time. Analysis by PCR fingerprinting confirmed the RAPD results. A second RAPD profile (VGII) was associated with infection in southwest Western Australia, where the two host eucalypts do not occur naturally. This raises the possibility of an alternative and as yet unidentified natural habitat of C. neoformans var. gattii. Our results indicate that RAPD analysis is a sensitive and useful method for investigating environmental sources of human infection with this biotype.
Journal of clinical microbiology
Sixty-one clinical and forty-nine environmental isolates of Cryptococcus neoformans var. gattii from Australia and the United States were analyzed by random amplification of polymorphic DNA (RAPD), using 12-to 22-mer primers in pairs, and/or PCR fingerprinting with a single primer derived from the microsatellite core sequence of the wild-type phage M13 (5 GAGGGTGGCGGTTCT 3). Three major genetic profiles were identified by both typing techniques. A single RAPD profile (VGI) predominated among clinical isolates (44 of 48, 92%) and isolates from host eucalypts (45 of 45, 100%) from Australia. Of the 94 Australian isolates, 4 (3 clinical and 1 environmental) were assigned to profile VGII; 2 of these were recovered from patients and one was recovered from plant debris from Western Australia. Only one Australian clinical isolate was assigned to profile VGIII
Clonality and Recombination in Genetically Differentiated Subgroups of Cryptococcus gattii
Eukaryotic Cell, 2005
Cryptococcus gattii is a pathogenic yeast that together with Cryptococcus neoformans causes cryptococcosis in humans and animals. High numbers of viable C. gattii propagules can be obtained from certain species of Australian Eucalyptus camaldulensis trees, and an epidemiological link between Eucalyptus colonization and human exposure has been proposed. However, the highest prevalence of C. gattii cryptococcosis occurs in Papua New Guinea and in regions of Australia where the eucalypt species implicated to date are not endemic. This study investigated the population structure of three geographically distinct clinical and veterinary populations of C. gattii from Australia and Papua New Guinea. All populations that consisted of a genotype found frequently in Australia (VGI) were strongly clonal and were highly differentiated from one another. Two populations of the less common VGII genotype from Sydney and the Northern Territory had population structures inferring recombination. In addition, there was some evidence of reduced genetic differentiation between these geographically remote regions. In a companion study presented in this issue, VGII isolates were overwhelmingly more fertile than those of the VGI genotype, giving biological support to the indirect assessment of sexual exchange. It appears that the VGI genotype propagates clonally on eucalypts in Australia and on an unknown substrate in Papua New Guinea, with infection initiated by an unidentified infectious propagule. VGII isolates are completing their life cycles and may be dispersed via sexually produced basidiospores, which are also likely to initiate respiratory infection.
Serotype and mating type characterization of Cryptococcus neoformans by Multiplex PCR
Revista Do Instituto De Medicina Tropical De Sao Paulo, 2007
Cryptococcus neoformans é levedura encapsulada, agente etiológico da criptococose. As espécies são comumente associadas com fezes de pombos e material vegetal. O objetivo do presente trabalho foi verificar a presença de leveduras em fezes de pombos e identificar os isolados em relação aos sorotipos e "mating types". Dez amostras de fezes de pombos foram coletadas na zona rural da cidade de Alfenas, Brasil. As amostras foram inoculadas em agar Niger e 22 isolados com características de C. neoformans foram obtidos. Os sorotipos e "mating types" foram determinados pela PCR multiplex e os sorotipos foram identificados também pelo Kit Crypto Check. Dentre as 22 amostras avaliadas, oito foram identificadas como C. neoformans através dos testes clássicos. Estas amostras foram caracterizadas como sorotipo A pelo Kit Crypto check e como sorotipo A MATa pela PCR multiplex. O presente estudo reforça a evidência de que as fezes de pombos constituem reservatório para C. neoformans e confirma a prevalência de C. neoformans var. grubii (Aa) nos isolados ambientais. PCR multiplex é uma alternativa aceitável para análise do sorotipo porque reduz os custos de cada reação e analisa simultaneamente os sorotipos e "mating type".