DRUG RESISTANCE IN THE PARASITE TRICHOMONAS VAGINALIS

这项研究的目的是为了了解 (S)人类寄生虫耐药的潜在机制， 阴道毛滴虫。对阴道毛滴虫耐药的菌株 美国唯一可用于治疗的药物甲硝唑出现 频率很低。我们的初步研究表明，有四种临床 对甲硝唑治疗无效的菌株有所减少 细胞内铁氧还蛋白及其mRNA的水平。铁氧还蛋白是一种 氢小体蛋白，需要将甲硝唑还原为其 细胞毒性形式。据我们所知，这是第一次展示 由于细胞不能进行化学作用而产生的抗药性 将药物修饰成其活性形式。此外，我们已经证明了 在其中两个耐药患者中，铁氧还蛋白基因转录减少 分离株。这表明，基因表达的调控是基础 抵抗的力量。拟议研究的具体目标是：1) 检查铁氧还蛋白的水平，以及其他氢酶体 参与药物激活的蛋白质，在额外的敏感 和抗性品系。耐药细胞系已经减少 将检测细胞内铁氧还蛋白的水平，以确定 铁氧还蛋白mRNA和/或基因转录发生改变。2)检查5‘ 铁氧还蛋白基因两侧的3‘序列在抗性和敏感性上 差异菌株，可能解释转录改变的原因 抗性品系中的基因。DNA序列基序，以及 与这种假定的转录调控元件结合，将是 学习。除了研究耐药性的机制外， 这些研究为探索这种基因的表达提供了一个框架。 原始的真核生物。因此，拟议的调查既涉及 在医学上和根本上都很重要的生物学方面 人类病原体。更好地了解潜在的机制 耐药性将是设计有效治疗方案的关键 用于治疗难治的病例。除了治疗之外 滴虫病、甲硝唑是治疗感染的常用药物 由其他厌氧生物引起，如内阿米巴、贾第鞭毛虫、 类杆菌和梭状芽孢杆菌。这些生物的分离株是 据报道，对这种药物具有相对抗药性，但实际上 关于抵抗的机制，我们一无所知。因此，我们的研究 阴道毛滴虫对甲硝唑耐药性的研究可能有助于 抗药性的基础是一些病原菌和原虫。

The objective of this research is to gain an understanding of the mechanism(s) underlying drug resistance in the human parasite, Trichomonas vaginalis. Strains of T. vaginalis that are resistant to metronidazole, the only drug available in the U.S. for treatment, arise at a low frequency. Our preliminary studies show that four clinical isolates, refractory to treatment with metronidazole, have decreased intracellular levels of ferredoxin and its mRNA. Ferredoxin is a hydrogenosomal protein which is required to reduce metronidazole to its cytotoxic form. To our knowledge, this is the first demonstration of drug resistance arising due to the inability of the cell to chemically modify a drug to its active form. Additionally, we have shown that ferredoxin gene transcription is reduced in two of these resistant isolates. This indicates that regulation of gene expression is the basis of resistance. The specific aims of the proposed studies are: 1) to examine the levels of ferredoxin, as well as other hydrogenosomal proteins which are involved in drug activation, in additional sensitive and resistant lines. Resistant cell lines which have decreased intracellular levels of ferredoxin will be examined to determine if ferredoxin mRNA and/or gene transcription is altered. 2)to examine the 5' and 3' sequences flanking the ferredoxin gene in resistant and sensitive strains for differences which might account for altered transcription of the gene in resistant lines. DNA sequence motifs, and the proteins which bind to such putative transcriptional regulatory elements, will be studied. In addition to examining the mechanism of drug resistance, these studies provide a framework for exploring gene expression in this primitive eukaryote. Thus, the proposed investigation addresses both medically and fundamentally important aspects of the biology of this human pathogen. A better knowledge of the mechanisms underlying resistance will be critical for designing effective treatment regimens for cases refractory to treatment. In addition to treating trichomoniasis, metronidazole is commonly used in treatment of infections caused by other anaerobic organisms, such as Entamoeba, Giardia, Bacteroides, and Clostridium. Isolates of these organisms which are relatively resistant to the drug have been reported, but virtually nothing is known regarding the mechanism of resistance. Thus our studies on metronidazole resistance in T. vaginalis may possibly shed light on the basis of resistance in a number of pathogenic bacteria and protozoa.