Candidate transmission survival genome of Mycobacterium tuberculosis-CRISPRi Screen I

Mycobacterium tuberculosis (Mtb), a leading cause of death from infection, completes its life cycle entirely in humans except for transmission through the air. To begin to understand how Mtb survives aerosolization, we mimicked liquid and atmospheric conditions experienced by Mtb before and after exhalation using a model aerosol fluid (MAF) based on the water-soluble, lipidic and cellular constituents of necrotic tuberculosis lesions. MAF induced drug tolerance in Mtb, remodeled its transcriptome and protected Mtb from dying in microdroplets desiccating in air. Yet survival was not passive: Mtb appeared to rely on hundreds of genes to survive conditions associated with transmission. Essential genes subserving proteostasis offered most protection. A large number of conventionally nonessential genes appeared to contribute as well, including genes encoding proteins that resemble anti-desiccants. The candidate transmission survival genome of Mtb may offer opportunities to reduce transmission of tuberculosis. These results are part of CRISPRi Screen I reported in this study.

结核分枝杆菌（Mycobacterium tuberculosis，Mtb）是引发感染性死亡的主要致病菌之一，其完整生命周期仅在人体内完成，仅传播过程需通过空气途径实现。为探究Mtb如何耐受气溶胶化过程，研究团队基于坏死性结核病灶的水溶性、脂类及细胞组分构建了模型气溶胶流体（model aerosol fluid，MAF），以此模拟Mtb在被呼出前后所经历的液体环境与大气环境。实验结果显示，MAF可诱导Mtb产生药物耐受性，重塑其转录组，并能保护Mtb在空气中干燥脱水形成的微滴中免于死亡。然而此种存活并非被动机制：Mtb似乎需要依靠数百个基因来应对与传播相关的环境压力，从而完成存活。其中，参与蛋白质稳态的必需基因发挥了主要的保护作用；此外还有大量传统意义上的非必需基因也参与了该过程，包括编码类似抗干燥蛋白的基因。结核分枝杆菌的传播存活候选基因组或可为降低结核传播提供新的干预靶点。本研究的相关结果均来自本研究中报道的CRISPR干扰（CRISPRi）筛选实验I。