Exit mechanisms from dormancy in M. tuberculosis and their involvement in the transition from latent to active disease

• Applicant: Alexander Sturm, Ph.D.
• Subject Area: Parasitology and Biology of Tropical Infectious Disease Pathogens
• Term: from 2016 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 298854910

To date tuberculosis is the most prevalent infectious disease, affecting two billion people worldwide. Its success relies predominantly on the extraordinary ability of Mycobacterium tuberculosis to persist in the human body, remaining inactive for decades. Yet, it retains the potential to proliferate again and cause active disease by colonizing the lungs, which if untreated is fatal. Its metabolically inactive or non-replicative state allows survival of antibiotic treatment and host immune defenses, whereas actively growing pathogen is more effectively killed by antibiotics. The non-replicating phenotype is thus the major obstacle in the treatment of tuberculosis, which has led to the standard six-month antibiotic therapy, which has serious side effects for the patient. In order to be able to control the course of the disease and improve antibiotic treatment, I am proposing to investigate the transition from the non-replicating to the growing phenotype of M. tuberculosis. I intend to use the in vitro carbon-starvation model that renders M. tuberculosis antibiotic tolerant and is thus considered a proxy to the non-replicating state in vivo. I have access to a transposon mutant library that covers the entirety of the non-essential genome with which I will perform high throughput genomic screens and Tn-seq sequencing. Preliminary RNA-seq data suggest approximately 300 genes responding immediately within the first minutes of resuscitation, most of which have not yet been characterized. I will also follow up these results using genetic and biochemical methods. In addition, I propose a method to isolate stochastically formed persisters using a fluorescent metabolic marker based on FRET and FACS. Both approaches will contribute to understanding exit mechanisms from the non-replicating state and in the long term have the potential to improve tuberculosis therapy.

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Deborah Hung, Ph.D.