Clonality and recombination in genetically differentiated subgroups of Cryptococcus gattii
Clonality and recombination in genetically differentiated subgroups of Cryptococcus gattii
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DOI：
10.1128/ec.4.8.1403-1409.2005
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发表时间：
2005-08-01
期刊：
影响因子：
--
通讯作者：
Carter, D
中科院分区：
文献类型：
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作者：
Campbell, LT;Currie, BJ;Carter, D
格特隐球菌是一种致病性酵母菌，与新型隐球菌一起引起人类和动物的隐球菌病。高活性C。gattii繁殖体可以从某些种类的澳大利亚赤桉（Eucalyptus camaldulensis）树木中获得，并且已经提出了桉树定殖和人类接触之间的流行病学联系。然而，C.格特隐球菌病发生在巴布亚新几内亚和澳大利亚的一些地区，在这些地区，迄今为止所涉及的真隐球菌属不是地方性的。本研究调查了来自澳大利亚和巴布亚新几内亚的三个地理上不同的临床和兽医群体的格特隐孢子虫的种群结构。所有的人口组成的基因型经常在澳大利亚（VGI）是强烈的克隆和高度分化。来自悉尼和北领地的不太常见的VGII基因型的两个群体具有推断重组的群体结构。此外，有一些证据表明，这些地理偏远地区之间的遗传分化减少。在这一问题上提出的一个同伴研究中，VGII分离物比VGI基因型的分离物具有压倒性的生育能力，为性交换的间接评估提供了生物学支持。似乎VGI基因型在澳大利亚的真核生物和巴布亚新几内亚的未知底物上克隆繁殖，感染由未鉴定的感染性繁殖体启动。VGII分离株正在完成其生命周期，并可能通过有性产生的担孢子传播，这也可能引发呼吸道感染。
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.