Non-cyp51A-mutation Mediated Triazole Resistance in Aspergillus fumigatus

克服烟曲霉中三唑抗性的关键障碍是显著缺乏 了解其遗传和分子基础。我们已经证明，已知的耐药机制确实 不能完全解释大多数临床分离株中观察到的耐药性。我们的长期目标是改善抗真菌药物 治疗，并确保三唑类药物用于治疗由 曲霉属。我们的中心假设是，非cyp 51 A突变介导的机制是必不可少的， 三唑耐药的临床分离的A.烟曲霉和涉及复杂的遗传变化改变1）甾醇 生物合成及其转录激活，2）三唑转运及其转录激活，以及3）迄今为止 未知的机制。我们目前的目标是通过识别基因， 和非cyp 51 A突变介导的抗性的分子决定簇。我们的初步数据显示， 虽然cyp 51 A在三唑耐药临床分离株中的突变是常见的，但它们对 阻力很小。我们已经观察到基因突变，这是我们收集的耐药分离株所特有的， 编码甾醇感应蛋白、甾醇生物合成的调节剂和甾醇生物合成酶。我们有 我还观察到临床分离株不仅过表达cyp 51 A，而且过表达麦角甾醇生物合成的大多数基因 途径，表明其组成性激活。我们观察到几个潜在的转运体- 在我们收集的三唑耐药分离株中， 被这些运输者。我们还表明，A.烟曲霉通过以下途径摄取三唑类抗真菌剂 促进扩散，我们相信改变三唑进口可能代表了一个重要的机制， 阻力为了实现我们的目标，我们将进行实验，以了解 遗传和分子决定因素通过改变甾醇生物合成或其 转录激活（Aim 1）和三唑转运及其调控（Aim 2）。在目标3中，我们还将利用 无偏见的全基因组比较，加上体外进化实验，以确定完全新的 临床分离株的耐药机制。我们的方法是创新的，因为我们将使用最新的基因和 基因组技术研究和发现新的非cyp 51 A突变介导的三唑机制 在美国境内活动的抵抗组织基于收集的三唑耐药临床分离株。拟议 研究是重要的，因为它代表了一个全面的分析的分子和遗传基础的非， cyp 51 A突变介导的A.并将提供新的见解的方式， 可以提高三唑对这种重要的人类病原体的活性。

A critical barrier to overcoming triazole resistance in Aspergillus fumigatus is the significant lack of understanding of its genetic and molecular basis. We have shown that the known mechanisms of resistance do not fully explain resistance observed among most clinical isolates. Our long-term goal is to improve antifungal therapy and ensure the sustained clinical utility of the triazole class for treatment of infections caused by Aspergillus species. Our central hypothesis is that non-cyp51A-mutation mediated mechanisms are essential to triazole resistance in clinical isolates of A. fumigatus and involve complex genetic changes altering 1) sterol biosynthesis and its transcriptional activation, 2) triazole transport and its transcriptional activation, and 3) as yet unknown mechanisms. Our current objective is to address critical knowledge gaps by identifying the genetic and molecular determinants of non-cyp51A-mutation mediated resistance. Our preliminary data suggest that while mutations in cyp51A among triazole resistant clinical isolates are common, their overall contribution to resistance is minimal. We have observed mutations, unique to resistant isolates in our collection, in genes encoding sterol sensing proteins, regulators of sterol biosynthesis, and sterol biosynthesis enzymes. We have also observed clinical isolates that overexpress not only cyp51A, but most genes of the ergosterol biosynthesis pathway, suggesting its constitutive activation. We have observed several potential transporters that are up- regulated among triazole resistant isolates in our collection, suggesting a role for triazole efflux and resistance by these transporters. We have also shown that clinical isolates of A. fumigatus take up triazole antifungals via facilitated diffusion and we believe that altered triazole import may represent an important mechanism of resistance. To accomplish our objective we will undertake experiments that will lead to an understanding of what genetic and molecular determinants influence triazole susceptibility through altered sterol biosynthesis or its transcriptional activation (Aim 1) and triazole transport and its regulation (Aim 2). In Aim 3, we will also utilize an unbiased whole genome comparisons, coupled with in vitro evolution experiments, to identify completely novel mechanisms of resistance in clinical isolates. Our approach is innovative as we will use the latest genetic and genomic techniques to study and discover novel non-cyp51A-mutation mediated mechanisms of triazole resistance that are operative in a U.S.-based collection of triazole resistant clinical isolates. The proposed research is significant as it represents a comprehensive analysis of the molecular and genetic basis of non- cyp51A-mutation mediated triazole resistance in A. fumigatus and will provide novel insights into ways in which triazole activity can be improved against this important human pathogen.