DRUG RESISTANCE IN THE PARASITE TRICHOMONAS VAGINALIS

本研究的目的是了解 人类寄生虫耐药性的潜在机制， 阴道毛滴虫 木霉菌株抵抗 甲硝唑是美国唯一可用的治疗药物， 在低频率下。 我们的初步研究表明，四个临床 甲硝唑治疗无效的分离株， 铁氧还蛋白及其mRNA的细胞内水平。 铁氧还蛋白是一种 氢化酶体蛋白，其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 由于细胞不能化学地 将药物改变成活性形式。 此外，我们还表明， 铁氧还蛋白基因的转录在两种耐药的 分离株 这表明基因表达调控是 抗战 建议研究的具体目的是：1） 检查铁氧还蛋白的水平，以及其他氢小体 参与药物活化的蛋白质，在另外的敏感性中， 和抗性品系。 减少的耐药细胞系 将检查铁氧还蛋白的细胞内水平以确定是否 铁氧还蛋白mRNA和/或基因转录被改变。（2）检查5' 和3'侧接铁氧还蛋白基因的序列， 菌株的差异，这可能会解释改变转录 抗性品系中的基因。 DNA序列基序，和蛋白质， 结合到这些假定的转录调控元件，将是 研究了 除了研究耐药性的机制外， 这些研究提供了一个框架，探索基因表达， 原始真核生物 因此，拟议的调查涉及两个方面 从医学上和生物学上来说， 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 治疗难治性病例 除了治疗 滴虫病，甲硝唑是常用的治疗感染 由其他厌氧生物引起，如内阿米巴，贾第虫， 拟杆菌属和梭菌属。 这些微生物的分离株， 据报道，对该药物具有相对耐药性，但实际上 关于耐药机制还不清楚。 因此，我们的研究 T.流浪者可能会揭示 耐药的基础是一些致病菌和原生动物。

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.