Low diversity Cryptococcus neoformans variety grubii multilocus sequence types from Thailand are consistent with an ancestral African origin.

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The evolution of Cryptococcus neoformans var. grubii in the context of clinical disease using multilocus sequence typing

The global burden of HIV-associated cryptococcal meningitis (CM) is estimated at one million cases per year, causing up to a third of all AIDS-related deaths. Cryptococcus neoformans variety grubii (Cng) is the most ubiquitous cause of cryptococcal meningitis worldwide, however patterns of molecular diversity are understudied across some geographical regions experiencing significant burdens of disease. Cryptococcus species are notable in the degree that virulence differs amongst lineages, and highly virulent emerging lineages are changing patterns of human disease both temporally and spatially. Molecular epidemiology constitutes the main methodology for understanding the factors underpinning the emergence of this understudied, yet increasingly important, group of pathogenic fungi. A multilocus sequence typing (MLST) scheme was used to characterise a genetically depauperate Cng population in Thailand, and a contrastingly highly diverse Cng population in Cape Town, South Africa. Sequence types (STs) from these populations were integrated into a dataset comprising global STs of Cng and patterns of range expansion were traced. Evidence from haplotypic networks and coalescent analyses revealed an ancestral African population of molecular type VNB, from which emerged a VNI lineage. This VNI lineage expanded globally out of Africa and led to the introduction of a limited number of genotypes in novel regions, including Asia. Bayesian inference estimated this spread of VNI to have occurred between 1 600 and 70 500 years ago, putatively vectored by the anthropogenically mediated spread of domesticated pigeons, historically native African birds. Clinical data collected from patients presenting with AIDS-associated CM showed that infecting African Cng isolates were associated with poorer long-term survival compared to Asian isolates. As mortality rates reported for these patients in Sub-Saharan Africa are higher than those seen in Asia, supported by a Galleria mellonella virulence model, this apparently elevated virulence is postulated as being the result of recombinant progeny with diverse phenotypes being created through frequent meiotic recombination

The evolution of Cryptococcus neoformans var. grubii in the context of clinical disease using multilocus sequence typing

The global burden of HIV-associated cryptococcal meningitis (CM) is estimated at one million cases per year, causing up to a third of all AIDS-related deaths. Cryptococcus neoformans variety grubii (Cng) is the most ubiquitous cause of cryptococcal meningitis worldwide, however patterns of molecular diversity are understudied across some geographical regions experiencing significant burdens of disease. Cryptococcus species are notable in the degree that virulence differs amongst lineages, and highly virulent emerging lineages are changing patterns of human disease both temporally and spatially. Molecular epidemiology constitutes the main methodology for understanding the factors underpinning the emergence of this understudied, yet increasingly important, group of pathogenic fungi. A multilocus sequence typing (MLST) scheme was used to characterise a genetically depauperate Cng population in Thailand, and a contrastingly highly diverse Cng population in Cape Town, South Africa. Sequence types (STs) from these populations were integrated into a dataset comprising global STs of Cng and patterns of range expansion were traced. Evidence from haplotypic networks and coalescent analyses revealed an ancestral African population of molecular type VNB, from which emerged a VNI lineage. This VNI lineage expanded globally out of Africa and led to the introduction of a limited number of genotypes in novel regions, including Asia. Bayesian inference estimated this spread of VNI to have occurred between 1 600 and 70 500 years ago, putatively vectored by the anthropogenically mediated spread of domesticated pigeons, historically native African birds. Clinical data collected from patients presenting with AIDS-associated CM showed that infecting African Cng isolates were associated with poorer long-term survival compared to Asian isolates. As mortality rates reported for these patients in Sub-Saharan Africa are higher than those seen in Asia, supported by a Galleria mellonella virulence model, this apparently elevated virulence is postulated as being the result of recombinant progeny with diverse phenotypes being created through frequent meiotic recombination.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Geographically structured populations of Cryptococcus neoformans Variety grubii in Asia correlate with HIV status and show a clonal population structure.

Contains fulltext : 125490.pdf (publisher's version ) (Open Access)Cryptococcosis is an important fungal disease in Asia with an estimated 140,000 new infections annually the majority of which occurs in patients suffering from HIV/AIDS. Cryptococcus neoformans variety grubii (serotype A) is the major causative agent of this disease. In the present study, multilocus sequence typing (MLST) using the ISHAM MLST consensus scheme for the C. neoformans/C. gattii species complex was used to analyse nucleotide polymorphisms among 476 isolates of this pathogen obtained from 8 Asian countries. Population genetic analysis showed that the Asian C. neoformans var. grubii population shows limited genetic diversity and demonstrates a largely clonal mode of reproduction when compared with the global MLST dataset. HIV-status, sequence types and geography were found to be confounded. However, a correlation between sequence types and isolates from HIV-negative patients was observed among the Asian isolates. Observations of high gene flow between the Middle Eastern and the Southeastern Asian populations suggest that immigrant workers in the Middle East were originally infected in Southeastern Asia

Consensus multi-locus sequence typing scheme for Cryptococcus neoformans and Cryptococcus gattii

This communication describes the consensus multi-locus typing scheme established by the Cryptococcal Working Group I (Genotyping of Cryptococcus neoformans and C. gattii) of the International Society for Human and Animal Mycology (ISHAM) using seven unlinked genetic loci for global strain genotyping. These genetic loci include the housekeeping genes CAP59,GPD1, LAC1, PLB1, SOD1, URA5 and the IGS1 region. Allele and sequence type information are accessible at http://www.mlst.net/