Remains of 17th century bishop support neolithic emergence of
tuberculosis

Date:
August 14, 2020
Source:
Max Planck Institute for the Science of Human History
Summary:
Researchers present analysis of the highest quality ancient
Mycobacterium tuberculosis genome to date, suggesting the pathogen
is much younger than previously believed.



FULL STORY ==========================================================================
When Anthropologist Caroline Arcini and her colleagues at the Swedish
Natural Historical Museum discovered small calcifications in the
extremely well preserved lungs of Bishop Peder Winstrup, they knew more investigation was needed. "We suspected these were remnants of a past
lung infection," says Arcini, "and tuberculosis was at the top of our
list of candidates. DNA analysis was the best way to prove it."

==========================================================================
Up to one quarter of the world's population is suspected to have been
exposed to bacteria of the Mycobacterium tuberculosis complex, which
cause tuberculosis (TB). Bishop Winstrup would have been one of many to
fall ill during the onset of the so-called "White Plague" TB pandemic
that ravaged post-medieval Europe.

Today, TB is among the most prevalent diseases, accounting for the
highest worldwide mortality from a bacterial infection.

The global distribution of TB has led to the prevailing assumption that
the pathogen evolved early in human history and reached its global
distribution via the hallmark Out of Africa human migrations tens of
thousands of years ago, but recent work on ancient TB genomes has stirred
up controversy over when this host-pathogen relationship began. In 2014,
a team led by scientists from the University of Tu"bingen and Arizona
State University reconstructed three ancient TB genomes from pre-contact
South America -- not only were the ancient strains unexpectedly related
to those circulating in present-day seals, but comparison against a large number of human strains suggested that TB emerged within the last 6000
years. Understandably, skepticism surrounded this new estimate since
it was based entirely on ancient genomes that are not representative of
the TB strains associated with humans today.

"Discovery of the Bishop's lung calcification gave us the opportunity to revisit the question of tuberculosis emergence with data from an ancient European," comments Kirsten Bos, group leader for Molecular Paleopathology
at the Max Planck Institute for the Science of Human History (MPI-SHH),
who co-led the study. "If we could reconstruct a TB genome from Bishop Winstrup, where we know his date of death to the day, it would give a
secure and independent calibration for our estimates of how old TB,
as we know it, actually is." The highest quality ancient TB genome
to date In a new study published this week in Genome Biology, Susanna
Sabin of MPI-SHH and colleagues reconstruct a tuberculosis genome from
the calcified nodule discovered in Bishop Winstrup's remains.



==========================================================================
"The genome is of incredible quality -- preservation on this scale is
extremely rare in ancient DNA," comments Bos.

Together with a handful of tuberculosis genomes from other work,
the researchers revisit the question of the age of the Mycobacterium tuberculosis complex, with the year of the Bishop's death as a fine-tuned calibration point.

Using multiple molecular dating models, all angles indeed point to a
relatively young age of the Mycobacterium tuberculosis complex.

"A more recent emergence of the tuberculosis pathogen complex is now
supported by genetic evidence from multiple geographic regions and time periods," comments Sabin, first author of the study. "It's the strongest evidence available to date for this emergence having been a Neolithic phenomenon." This most recent shift in the narrative for when bacteria in
the Mycobacterium tuberculosis complex became highly infectious to humans raises further questions about the context of its emergence, as it appears
to have coincided with the rise of pastoralism and sedentary lifestyles.

"The Neolithic transition seems to have played an important role for the emergence of a number of human pathogens," comments Denise Ku"hnert,
group leader for disease transmission research at MPI-SHH who co-led
the investigation.

"For TB in particular, stronger evidence could only come from an
older genome, though these deeper time periods are unlikely to yield preservation on the scale of what we've seen for Bishop Winstrup,"
adds Bos.

"Moving forward," Sabin further comments, "the hope is we will find
adequately preserved DNA from time periods close to the emergence of
the complex, or perhaps from its ancestor."

========================================================================== Story Source: Materials provided by Max_Planck_Institute_for_the_Science_of_Human_History.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Susanna Sabin, Alexander Herbig, AAshild J. Vaagene, Torbjo"rn
Ahlstro"m,
Gracijela Bozovic, Caroline Arcini, Denise Ku"hnert, Kirsten
I. Bos. A seventeenth-century Mycobacterium tuberculosis
genome supports a Neolithic emergence of the Mycobacterium
tuberculosis complex. Genome Biology, 2020; 21 (1) DOI:
10.1186/s13059-020-02112-1 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200814123209.htm

--- up 4 weeks, 2 days, 1 hour, 55 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1337:3/111)