ORCID Profile
0000-0002-9528-1495
Current Organisations
University of Bath
,
University of Bristol
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Publisher: Springer Science and Business Media LLC
Date: 10-2005
DOI: 10.1038/NATURE04220
Abstract: Genealogy can illuminate the evolutionary path of important human pathogens. In some microbes, strict clonal reproduction predominates, as with the worldwide dissemination of Mycobacterium leprae, the cause of leprosy. In other pathogens, sexual reproduction yields clones with novel attributes, for ex le, enabling the efficient, oral transmission of the parasite Toxoplasma gondii. However, the roles of clonal or sexual propagation in the origins of many other microbial pathogen outbreaks remain unknown, like the recent fungal meningoencephalitis outbreak on Vancouver Island, Canada, caused by Cryptococcus gattii. Here we show that the C. gattii outbreak isolates comprise two distinct genotypes. The majority of isolates are hypervirulent and have an identical genotype that is unique to the Pacific Northwest. A minority of the isolates are significantly less virulent and share an identical genotype with fertile isolates from an Australian recombining population. Genotypic analysis reveals evidence of sexual reproduction, in which the majority genotype is the predicted offspring. However, instead of the classic a-alpha sexual cycle, the majority outbreak clone appears to have descended from two alpha mating-type parents. Analysis of nuclear content revealed a diploid environmental isolate homozygous for the major genotype, an intermediate produced during same-sex mating. These studies demonstrate how cryptic same-sex reproduction can enable expansion of a human pathogen to a new geographical niche and contribute to the ongoing production of infectious spores. This has implications for the emergence of other microbial pathogens and inbreeding in host range expansion in the fungal and other kingdoms.
Publisher: Oxford University Press (OUP)
Date: 06-2006
DOI: 10.1111/J.1567-1364.2006.00075.X
Abstract: Biological ersity has been estimated for various phyla of life, such as insects and mammals, but in the microbe world is has been difficult to determine species richness and abundance. Here we describe a study of species ersity of fungi with a yeast-like colony morphology from the San Juan Islands, a group of islands that lies southeast of Vancouver Island, Canada. Our s ling revealed that the San Juan archipelago biosphere contains a erse range of such fungi predominantly belonging to the Basidiomycota, particularly of the order Tremellales. One member of this group, Cryptococcus gattii, is the etiological agent of a current and ongoing outbreak of cryptococcosis on nearby Vancouver Island. Our s ling did not, however, reveal this species. While the lack of recovery of C. gattii does not preclude its presence on the San Juan Islands, our results suggest that the Strait of Juan de Fuca may be serving as a geographical barrier to restrict the dispersal of this primary human fungal pathogen into the United States.
Publisher: Public Library of Science (PLoS)
Date: 09-11-2004
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Stephanie Diezmann.