The evolution of drug resistance in clinical isolates of Candida albicans.
The evolution of drug resistance in clinical isolates of Candida albicans.
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DOI：
10.7554/elife.00662
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发表时间：
2015-02-03
期刊：
影响因子：
7.7
通讯作者：
Regev A
中科院分区：
文献类型：
--
作者：
Ford CB;Funt JM;Abbey D;Issi L;Guiducci C;Martinez DA;Delorey T;Li BY;White TC;Cuomo C;Rao RP;Berman J;Thompson DA;Regev A
白色念珠菌既是健康人类微生物组的成员，也是免疫功能低下个体的主要病原体。感染通常用麦角固醇生物合成的唑类抑制剂治疗，通常导致耐药性。对临床分离株的研究涉及耐药性的多种机制，但主要集中在大规模畸变或候选基因上，没有全面描绘适应的遗传基础。在这里，我们利用下一代测序技术分析了来自11名口腔念珠菌病患者的43株分离株。我们检测了新选择的突变，包括单核苷酸多态性（SNP），拷贝数变异和杂合性丢失（洛）事件。洛缺失事件通常与获得性抗性相关，240个基因的SNPs可能与宿主适应性相关。相反，大多数非整倍体是短暂的，与耐药性无关。我们的分析还表明，分离株也不同的粘附，粘附，和毒力。我们的工作揭示了耐药性和宿主适应进化的新分子机制。DOI：http://dx.doi.org/10.7554/eLife.00662.001几乎所有的人都感染了真菌白色念珠菌。在大多数人中，感染不会产生任何症状，因为他们的免疫系统能够抵消真菌在身体周围传播的企图。然而，如果真菌攻击和身体防御之间的平衡失败，真菌能够传播，这可能导致严重的疾病，在42%的情况下是致命的。C.白色念珠菌会战胜人体的防御能力而致病吗这是一个相关的问题，因为最有效的抗真菌药物，包括药物氟康唑，并不能杀死真菌;他们只是阻止它的生长。这使真菌有时间通过快速替换药物破坏的真菌蛋白质或有效地将药物从其细胞中清除来产生抗药性。在这项研究中，福特等人研究了C.接受氟康唑治疗的患者随着时间的推移出现白色念珠菌。福特等人采集了43份C. 11名免疫系统较弱的患者。实验表明，早期采集的真菌样品比后期采集的样品对药物更敏感。在大多数情况下，遗传数据表明，感染开始与一个单一的真菌细胞;细胞在后来的样本是它的后代。尽管如此，来自同一患者的样本之间存在大量遗传变异，这表明真菌面临着对药物更具抗药性的压力。有240个基因包括那些可以改变真菌细胞表面使其更好地逃避宿主免疫系统的基因随着时间的推移在三个或更多的患者中发生了微小的变化。实验室测试显示，这些基因中的许多基因可能对真菌在药物存在的情况下在动物宿主中存活很重要。C.白色念珠菌细胞通常具有每个基因的两个遗传上不同的拷贝。福特等人发现，对于某些基因，包括一些制造表面成分或参与将药物从细胞中排出的基因，一个拷贝的遗传信息丢失，使两个拷贝变得相同，与氟康唑耐药性有关。然而，整个或部分染色体的获得-其中包含大量的基因-与抗性无关，但可能提供额外的遗传物质，用于在酵母菌群中产生多样性，这可能有助于细胞在未来进化抗性。这些实验已经确定了许多新的候选基因，这些基因对耐药性和逃避宿主免疫系统非常重要，并且可以用于指导新疗法的开发，以治疗这些危及生命的感染。DOI：http://dx.doi.org/10.7554/eLife.00662.002网站
Candida albicans is both a member of the healthy human microbiome and a major pathogen in immunocompromised individuals. Infections are typically treated with azole inhibitors of ergosterol biosynthesis often leading to drug resistance. Studies in clinical isolates have implicated multiple mechanisms in resistance, but have focused on large-scale aberrations or candidate genes, and do not comprehensively chart the genetic basis of adaptation. Here, we leveraged next-generation sequencing to analyze 43 isolates from 11 oral candidiasis patients. We detected newly selected mutations, including single-nucleotide polymorphisms (SNPs), copy-number variations and loss-of-heterozygosity (LOH) events. LOH events were commonly associated with acquired resistance, and SNPs in 240 genes may be related to host adaptation. Conversely, most aneuploidies were transient and did not correlate with drug resistance. Our analysis also shows that isolates also varied in adherence, filamentation, and virulence. Our work reveals new molecular mechanisms underlying the evolution of drug resistance and host adaptation. DOI: http://dx.doi.org/10.7554/eLife.00662.001 Nearly all humans are infected with the fungus Candida albicans. In most people, the infection does not produce any symptoms because their immune system is able to counteract the fungus' attempts to spread around the body. However, if the balance between fungal attack and body defence fails, the fungus is able to spread, which can lead to serious disease that is fatal in 42% of cases. How does C. albicans outcompete the body's defences to cause disease? This is a pertinent question because the most effective antifungal medicines—including the drug fluconazole—do not kill the fungus; they only stop it from growing. This gives the fungus time to develop resistance to the drug by becoming able to quickly replace the fungal proteins the drug destroys, or to efficiently remove the drug from its cells. In this study, Ford et al. studied the changes that occur in the DNA of C. albicans over time in patients who are being treated with fluconazole. Ford et al. took 43 samples of C. albicans from 11 patients with weakened immune systems. The experiments show that the fungus samples collected early on were more sensitive to the drug than the samples collected later. In most cases, the genetic data suggest that the infections begin with a single fungal cell; the cells in the later samples are its offspring. Despite this, there is a lot of genetic variation between samples from the same patient, which indicates that the fungus is under pressure to become more resistant to the drug. There were 240 genes—including those that can alter the surface on the fungus cells to make it better at evading the host immune system—in which small changes occurred over time in three or more patients. Laboratory tests revealed that many of these genes are likely important for the fungus to survive in an animal host in the presence of the drug. C. albicans cells usually have two genetically distinct copies of every gene. Ford et al. found that for some genes—including some that make surface components or are involved in expelling drugs from cells—the loss of genetic information from one copy, so that both copies become identical, is linked to resistance to fluconazole. However, the gain of whole or partial chromosomes—which contain large numbers of genes—is not linked to resistance, but may provide additional genetic material for generating diversity in the yeast population that may help the cells to evolve resistance in the future. These experiments have identified many new candidate genes that are important for drug resistance and evading the host immune system, and which could be used to guide the development of new therapeutics to treat these life-threatening infections. DOI: http://dx.doi.org/10.7554/eLife.00662.002