Abstract
ABSTRACTInfection with Mycobacterium tuberculosis causes a spectrum of outcomes; the majority of individuals contain but do not eliminate the infection, while a small subset present with primary active tuberculosis (TB) disease. This variability in infection outcomes is recapitulated at the granuloma level within each host, such that some sites of infection can be fully cleared while others progress. Understanding the spectrum of TB outcomes requires new tools to deconstruct the mechanisms underlying differences in granuloma fate. Here, we use novel genome-encoded barcodes to uniquely tag individual M. tuberculosis bacilli, enabling us to quantitatively track the trajectory of each infecting bacterium in a macaque model of TB. We also introduce a robust bioinformatics pipeline capable of identifying and counting barcode sequences within complex mixtures and at various read depths. By coupling this tagging strategy with serial positron emission tomography coregistered with computed tomography (PET/CT) imaging of lung pathology in macaques, we define a lesional map of M. tuberculosis infection dynamics. We find that there is no significant infection bottleneck, but there are significant constraints on productive bacterial trafficking out of primary granulomas. Our findings validate our barcoding approach and demonstrate its utility in probing lesion-specific biology and dissemination. This novel technology has the potential to greatly enhance our understanding of local dynamics in tuberculosis.
Highlights
Infection with Mycobacterium tuberculosis causes a spectrum of outcomes; the majority of individuals contain but do not eliminate the infection, while a small subset present with primary active tuberculosis (TB) disease
New tools are needed to dissect the local biology of M. tuberculosis infection, especially in the nonhuman primate (NHP) model, whose strengths are that it recapitulates the variable course of human infection and produces individual granulomas with pathology very similar to that found in humans [5, 10, 11]
We engineered a library of digitally barcoded plasmids that we introduced into Mycobacterium smegmatis and M. tuberculosis Erdman
Summary
Infection with Mycobacterium tuberculosis causes a spectrum of outcomes; the majority of individuals contain but do not eliminate the infection, while a small subset present with primary active tuberculosis (TB) disease. Dissection of lesion course in macaques has been transformed by the use of positron emission tomography coregistered with computed tomography (PET/CT) and an [18F]fluorodeoxyglucose radiotracer ([18F]FDG) and validated in humans [8, 12, 13] Using this approach, we previously demonstrated that formation of disseminated lesions early after infection, by which we mean the first 6 weeks postinfection, is associated with development of active disease, whereas limited early dissemination is associated with maintenance of clinically latent infection, suggesting that early dissemination is critical in determining host outcome [12]. As the previous study only used a panel of 8 bacterial strains, it did not allow us to unambiguously resolve the subsequent fate of each bacterium following infection
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
