Mycobacterium tuberculosis persistence mutants identified by screening in isoniazid-treated mice
Mycobacterium tuberculosis persistence mutants identified by screening in isoniazid-treated mice
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DOI：
10.1073/pnas.1003219107
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发表时间：
2010-07-06
影响因子：
11.1
通讯作者：
McKinney, John D.
中科院分区：
文献类型：
--
作者：
Dhar, Neeraj;McKinney, John D.
结核病(TB)是出了名的难以治愈，需要服用多种抗生素6摩尔以上。传统的抗结核药物抑制参与细胞生长和分裂的生物合成过程，如DNA复制、RNA转录、蛋白质翻译和细胞壁生物发生。虽然这些抗生素在最佳生长条件下对体外培养的细菌非常有效，但对哺乳动物体内组织中生长的细菌效果较差。在体内生长的细菌产生抗生素耐受性的因素尚不清楚，尽管新陈代谢改变和生长缓慢被假设起到了作用。为了解决这个问题，我们确定了结核分枝杆菌的突变，这些突变损害或增强了使用异烟肼(INH)治疗的小鼠的持久性，异烟肼是一种一线抗结核病药物。编码假定的ATP结合盒转运子亚单位的CyDC的破坏，加速了异烟肼治疗的小鼠的细菌清除，而不影响未治疗的小鼠的生长或存活。相反，rv0096-rv0101基因簇中的转座子插入减弱了未经治疗的小鼠的细菌生长和存活，但矛盾地阻止了异烟肼介导的对治疗小鼠的细菌杀灭。这些不同的表型依赖于细菌与组织环境的相互作用，因为这两个突变株在体外巨噬细胞或体外无菌培养中对异烟肼反应正常。我们的发现具有重要的意义，因为传统的基因筛查将遗漏损害持久性的突变，以识别候选药物靶点。相反，标准的诊断方法会错过持久性增强的突变，这些方法是在体外培养的细菌上进行的，以检测耐药性。
Tuberculosis (TB) is notoriously difficult to cure, requiring administration of multiple antibiotics for 6 moor longer. Conventionalanti-TB drugs inhibit biosynthetic processes involved in cell growth and division, such as DNA replication, RNA transcription, protein translation, and cell wall biogenesis. Although highly effective against bacteria cultured in vitro under optimal growth conditions, these antibiotics are less effective against bacteria grown in vivo in the tissues of a mammalian host. The factors that contribute to the antibiotic tolerance of bacteria grown in vivo are unknown, although altered metabolism and sluggish growth are hypothesized to play a role. To address this question, we identified mutations in Mycobacterium tuberculosis that impaired or enhanced persistence in mice treated with isoniazid (INH), a front-line anti-TB drug. Disruption of cydC, encoding a putative ATP-binding cassette transporter subunit, accelerated bacterial clearance in INH-treated mice without affecting growth or survival in untreated mice. Conversely, transposon insertions within the rv0096-rv0101 gene cluster attenuated bacterial growth and survival in untreated mice but paradoxically prevented INH-mediated killing of bacteria in treated mice. These contrasting phenotypes were dependent on the interaction of the bacteria with the tissue environment because both mutants responded normally to INH when grown in macrophages ex vivo or in axenic cultures in vitro. Our findings have important implications because persistence-impairing mutations would be missed by conventional genetic screens to identify candidate drug targets. Conversely, persistence-enhancing mutations would be missed by standard diagnostic methods, which are performed on bacteria grown in vitro, to detect drug resistance.