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Out Of Mesopotamia: Evolutionary History Of Tuberculosis

Date:
October 22, 2008
Source:
CNRS
Summary:
The evolutionary timing and spread of the Mycobacterium tuberculosis complex (MTBC), one of the most successful groups of bacterial pathogens, remains largely unknown. Using mycobacterial tandem repeat sequences as genetic markers, scientists show that the MTBC consists of two independent clades, one composed exclusively of M. tuberculosis lineages from humans and the other composed of both animal and human isolates.
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The evolutionary timing and spread of the Mycobacterium tuberculosis complex (MTBC), one of the most successful groups of bacterial pathogens, remains largely unknown. Here, using mycobacterial tandem repeat sequences as genetic markers, we show that the MTBC consists of two independent clades, one composed exclusively of M. tuberculosis lineages from humans and the other composed of both animal and human isolates.

The latter also likely derived from a human pathogenic lineage, supporting the hypothesis of an original human host. Using Bayesian statistics and experimental data on the variability of the mycobacterial markers in infected patients, we estimated the age of the MTBC at 40,000 years, coinciding with the expansion of “modern” human populations out of Africa. Moreover, the diversification of the oldest EAI and LAM populations took place during plant and animal domestication.

In the Fertile Crescent, 13,000 years ago, small nomadic hunter-gatherer groups were replaced by farming societies based on domesticated livestock and crops. This paramount event in human history was probably not without consequence for an epidemic, infectious disease such as tuberculosis, where crowded farming populations may have promoted high infection rates, bacterial spread and transition to new niches and animal hosts.

Furthermore, coalescence analysis revealed a strong and recent demographic expansion in almost all M. tuberculosis lineages, which coincides with the human population explosion over the last two centuries. These findings thus unveil the dynamic dimension of the association between human host and pathogen populations.


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The above story is based on materials provided by CNRS. Note: Materials may be edited for content and length.


Journal Reference:

  1. Wirth et al. Origin, Spread and Demography of the Mycobacterium tuberculosis Complex. PLoS Pathogens, 2008; 4 (9): e1000160 DOI: 10.1371/journal.ppat.1000160

Cite This Page:

CNRS. "Out Of Mesopotamia: Evolutionary History Of Tuberculosis." ScienceDaily. ScienceDaily, 22 October 2008. <www.sciencedaily.com/releases/2008/10/081017085214.htm>.
CNRS. (2008, October 22). Out Of Mesopotamia: Evolutionary History Of Tuberculosis. ScienceDaily. Retrieved May 25, 2015 from www.sciencedaily.com/releases/2008/10/081017085214.htm
CNRS. "Out Of Mesopotamia: Evolutionary History Of Tuberculosis." ScienceDaily. www.sciencedaily.com/releases/2008/10/081017085214.htm (accessed May 25, 2015).

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