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Nat Med. 2014 Jan;20(1):75-9. doi: 10.1038/nm.3412. Epub 2013 Dec 15.

Sterilization of granulomas is common in active and latent tuberculosis despite within-host variability in bacterial killing.

Author information

1
1] Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA. [2].
2
1] Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, USA. [2] Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA. [3].
3
Department of Radiology, Positron Emission Tomography Research Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
4
Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
5
Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, USA.
6
Department of Computer Science and Engineering, Texas A&M University, College Station, Texas, USA.
7
Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA.
8
1] Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, USA. [2] Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA. [3] Ragon Institute of MGH, MIT, and Harvard, Boston, Massachusetts, USA.

Abstract

Over 30% of the world's population is infected with Mycobacterium tuberculosis (Mtb), yet only ∼5-10% will develop clinical disease. Despite considerable effort, researchers understand little about what distinguishes individuals whose infection progresses to active tuberculosis (TB) from those whose infection remains latent for decades. The variable course of disease is recapitulated in cynomolgus macaques infected with Mtb. Active disease occurs in ∼45% of infected macaques and is defined by clinical, microbiologic and immunologic signs, whereas the remaining infected animals are clinically asymptomatic. Here, we use individually marked Mtb isolates and quantitative measures of culturable and cumulative bacterial burden to show that most lung lesions are probably founded by a single bacterium and reach similar maximum burdens. Despite this observation, the fate of individual lesions varies substantially within the same host. Notably, in active disease, the host sterilizes some lesions even while others progress. Our data suggest that lesional heterogeneity arises, in part, through differential killing of bacteria after the onset of adaptive immunity. Thus, individual lesions follow diverse and overlapping trajectories, suggesting that critical responses occur at a lesional level to ultimately determine the clinical outcome of infection. Defining the local factors that dictate outcome will be useful in developing effective interventions to prevent active TB.

PMID:
24336248
PMCID:
PMC3947310
DOI:
10.1038/nm.3412
[Indexed for MEDLINE]
Free PMC Article

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