Abstract：
Persistence of Mycobacterium tuberculosis (Mtb) is one of the challenges to successful treatment of tuberculosis (TB). In vitro models of non-replicating Mtb are used to test the efficacy of new molecules against Mtb persisters. The H37Ra strain is attenuated for growth in macrophages and mice. We validated H37Ra-infected immunocompetent mice for testing anti-TB molecules against slow/non-replicating Mtb in vivo. Swiss mice were infected intravenously with H37Ra and monitored for CFU burden and histopathology for a period of 12 weeks. The bacteria multiplied at a slow pace reaching a maximum load of ∼106 in 8-12 weeks depending on the infection dose, accompanied by time and dose-dependent histopathological changes in the lungs. Surprisingly, four-weeks of treatment with isoniazid-rifampicin-ethambutol-pyrazinamide combination caused only 0.4 log10 and 1 log10 reduction in CFUs in lungs and spleen respectively. The results show that ∼40 % of the H37Ra bacilli in lungs are persisters after 4 weeks of anti-TB therapy. Isoniazid/rifampicin monotherapy also showed similar results. A combination of bedaquiline and isoniazid reduced the CFU counts to <200 (limit of detection), compared to ∼5000 CFUs by isoniazid alone. The study demonstrates an in vivo model of Mtb persisters for testing new leads using a BSL-2 strain.
摘要：
结核分枝杆菌（Mtb）的持续存在是成功治疗结核病（TB）的挑战之一。非复制型Mtb的体外模型用于测试新分子对Mtb持久性的功效。H37Ra菌株在巨噬细胞和小鼠中的生长被减毒。我们验证了H37Ra感染的免疫活性小鼠在体内测试抗TB分子对抗缓慢/非复制型Mtb。瑞士小鼠用H37Ra静脉内感染,并监测CFU负荷和组织病理学12周。细菌以缓慢的速度繁殖，在8-12周内达到最大负荷约106，具体取决于感染剂量，伴随着时间和剂量依赖性的肺组织病理学变化。令人惊讶的是,异烟肼-利福平-乙胺丁醇-吡嗪酰胺联合治疗4周,仅导致肺和脾CFU分别减少0.4log10和1log10.结果显示，在4周的抗结核治疗后，肺中40%的H37Ra杆菌持续存在。异烟肼/利福平单药治疗也显示类似结果。bedaquiline和异烟肼的组合将CFU计数降低到<200（检测限），与单独使用异烟肼的5000CFU相比。该研究证明了使用BSL-2菌株测试新引线的Mtb持久性体内模型。
