A hidden battle in the dirt: Soil amoebae interactions with Paracoccidioides spp
A hidden battle in the dirt: Soil amoebae interactions with Paracoccidioides spp
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DOI：
10.1371/journal.pntd.0007742
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发表时间：
2019-10-01
影响因子：
3.8
通讯作者：
Silva-Pereira, Ildinete
中科院分区：
文献类型：
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作者：
Albuquerque, Patricia;Nicola, Andre Moraes;Silva-Pereira, Ildinete
拟球孢子菌属是热变型真菌，引起一种被忽视的热带疾病（副球孢子菌病），是拉丁美洲特有的。这些真菌栖息在土壤中，在那里它们作为生物体生活，不需要哺乳动物宿主来完成它们的生命周期。尽管如此，它们发展了复杂的毒力属性，使它们不仅能够在宿主组织中生存，而且还能引起疾病。一个假说的选择压力驱动的出现或维持土壤真菌的毒性是它们与土壤捕食者，如阿米巴和蠕虫的相互作用。我们评估了环境变形虫捕食者在土壤中的存在，从犰狳洞穴Paracoccidioides先前已被检测和测试，如果Paracoccidioides与变形虫的相互作用选择的真菌的毒力增加。线虫、纤毛虫和变形虫都是真菌的潜在捕食者，它们在土壤样本的培养物中生长。显微镜观察和ITS序列测定鉴定了变形虫为阿米巴属、Allovahlkampfia spelaea和蠕虫状阿米巴。这三种变形虫有效地摄取、杀死和消化副球孢子菌属。酵母细胞，如实验室适应的无菌卡氏阿米巴。拟球孢子菌与A. castellanii选择与真菌在天然捕食者以及鼠巨噬细胞和体内（Galleria mellonella和小鼠）中的存活相关的表型性状。毒力的这些变化与细胞壁α-葡聚糖的积累有关，这种多糖掩盖了宿主模式识别受体对真菌分子模式的识别。总之，我们的研究结果表明，Paracoccidioides栖息在一个复杂的环境中，有多个变形虫捕食者，可以施加选择压力，以指导毒力性状的进化。
Paracoccidioides spp. are thermodimorphic fungi that cause a neglected tropical disease (paracoccidioidomycosis) that is endemic to Latin America. These fungi inhabit the soil, where they live as saprophytes with no need for a mammalian host to complete their life cycle. Despite this, they developed sophisticated virulence attributes allowing them not only to survive in host tissues but also to cause disease. A hypothesis for selective pressures driving the emergence or maintenance of virulence of soil fungi is their interaction with soil predators such as amoebae and helminths. We evaluated the presence of environmental amoeboid predators in soil from armadillo burrows where Paracoccidioides had been previously detected and tested if the interaction of Paracoccidioides with amoebae selects for fungi with increased virulence. Nematodes, ciliates, and amoebae-all potential predators of fungi-grew in cultures from soil samples. Microscopical observation and ITS sequencing identified the amoebae as Acanthamoeba spp, Allovahlkampfia spelaea, and Vermamoeba vermiformis. These three amoebae efficiently ingested, killed and digested Paracoccidioides spp. yeast cells, as did laboratory adapted axenic Acanthamoeba castellanii. Sequential co-cultivation of Paracoccidioides with A. castellanii selected for phenotypical traits related to the survival of the fungus within a natural predator as well as in murine macrophages and in vivo (Galleria mellonella and mice). These changes in virulence were linked to the accumulation of cell wall alpha-glucans, polysaccharides that mask recognition of fungal molecular patterns by host pattern recognition receptors. Altogether, our results indicate that Paracoccidioides inhabits a complex environment with multiple amoeboid predators that can exert selective pressure to guide the evolution of virulence traits.