Researchers reconstruct genome of the Black Death

Oct 12, 2011
A skull from the East Smithfield plague pits in London, located under what is now the Royal Mint. Photo credit: Museum of London

led by researchers at McMaster University and the University of Tubingen in Germany -- has sequenced the entire genome of the Black Death, one of the most devastating epidemics in human history.

This marks the first time scientists have been able to draft a reconstructed of any ancient pathogen, which will allow researchers to track changes in the pathogen's and over time. This work -- currently published online in the scientific journal Nature -- could lead to a better understanding of modern .

Geneticists Hendrik Poinar and Kirsten Bos of McMaster University and Johannes Krause and Verena Schuenemann of the University of Tubingen collaborated with Brian Golding and David Earn of McMaster University, Hernán A. Burbano and Matthias Meyer of the Max Planck Institute for Evolutionary Anthropology and Sharon DeWitte of the University of South Carolina, among others.

In a separate study published recently, the team described a novel methodological approach to pull out tiny degraded DNA fragments of the causative agent of the , and showed that a specific variant of the Yersinia pestis bacterium, was responsible for the plague that killed 50 million Europeans between 1347 and 1351.

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Interview with Hendrik Poinar, associate professor and director of the McMaster Ancient DNA Centre and an investigator with the Michael G. DeGroote Insitute of Infectious Disease. Video: McMaster University

After this success, the next major step was to attempt to "capture" and sequence the entire genome, explains Poinar, associate professor and director of the McMaster Ancient DNA Centre and an investigator with the Michael G. DeGroote Institute of Infectious Disease Research, also at McMaster University.

"The genomic data show that this bacterial strain, or variant, is the ancestor of all modern plagues we have today worldwide. Every outbreak across the globe today stems from a descendant of the medieval plague," he says. "With a better understanding of the evolution of this deadly pathogen, we are entering a new era of research into infectious disease."

"Using the same methodology, it should now be possible to study the genomes of all sorts of historic pathogens," adds Krause, one of the lead authors of the study. "This will provide us with direct insights into the evolution of human and historical pandemics."

The direct descendants of the same bubonic plague continue to exist today, killing some 2,000 people each year.

"We found that in 660 years of evolution as a human pathogen, there have been relatively few changes in the genome of the ancient organism, but those changes, however small, may or may not account for the noted increased virulence of the bug that ravaged Europe," says Poinar. "The next step is to determine why this was so deadly."

Major technical advances in DNA recovery and sequencing have dramatically expanded the scope of genetic analysis of ancient specimens, opening new horizons in the understanding of emerging and re-emerging infections.

Mapping millions of small DNA fragments to the genome of modern plague pestis bacteria

DeWitte, Bos and Schuenemann analyzed skeletal remains from victims buried in the East Smithfield "plague pits" in London, located under what is now the Royal Mint. By targeting promising specimens -- which had been pre-screened for the presence of Y. pestis -- from the dental pulp of five bodies, they were able to extract, purify and enrich specifically for the pathogen's DNA, thereby decreasing the background DNA consisting of human, fungal and other non-plague DNA.

Linking the 1349-1350 dates of the skeletal remains to the genomic data allowed the researchers to calculate the age of the ancestor of the Yersinia pestis that caused the medieval plague. This date coalesced sometime between the 12th and 13th centuries, indicating that earlier plagues such as the Justinian plague of the 6th Century -- once thought to have been caused by the same pathogen -- was likely caused by another, yet to be determined. The Justinian spread across the Eastern Roman Empire, killing an estimated 100 million people worldwide.

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User comments : 8

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Cave_Man
1 / 5 (1) Oct 12, 2011
I always thought the black death was ebola? Man schools suck at teaching history.
kochevnik
not rated yet Oct 12, 2011
"Black Death" http://www.blackdeathmovie.com reigns as one of my all time favorite movies.
Simonsez
4 / 5 (2) Oct 12, 2011
I could have sworn there was an article here less than a month ago where scientists were claiming they have disproved the prevailing theory that bubonic plague was the Black Death. IIRC their thinking was that the Black Death had slightly different symptoms than bubonic plague, and that diseased rats could not have spread the epidemic quickly enough to match what was observed.
Simonsez
not rated yet Oct 12, 2011
Looks like that article I am thinking of was more than a month ago - there was one posted end of August that precedes this one.
http://medicalxpr...ath.html
Recovering_Human
4.2 / 5 (5) Oct 12, 2011
You could tell the skull was from a brit without even reading the caption.
Goresh
not rated yet Oct 13, 2011
Given that medieval doctors lacked DNA sequencing technology, it is very unlikely that every case diagnosed as "black death" was in fact caused by the same pathogen.

Nobody has any doubt that many if not most black death outbreaks were caused by Yersinia pestis. What I would like to see is dna seuences from the pathogen that caused deaths above the arctic circle for instance where rats cant live, or the english village that contained a black death outbreak through voluntary quarantine which rats of course would ignore.
Goresh
not rated yet Oct 13, 2011
In order to be the black death pathogen, it will need to be shown that it could pass directly and easily from person to person without the need for a rat vector.
If this particular sequence of Yersinia pestis cannot do that, then it clearly does not meet the observed transmission method of historical records and cannot hen be THE "black death"
Goresh
not rated yet Oct 13, 2011
"By targeting promising specimens -- which had been pre-screened for the presence of Y. pestis"

So the "proof" of this being black death hinges ob it being pre-tested for the pathogen and then using its "discovery" as comfirmation.

Hardly meets double blind standards does it.