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Black Death genome reconstructed


October 13, 2011

Five skeletal remains from the East Smithfield site (Photo: Museum of London)

Five skeletal remains from the East Smithfield site (Photo: Museum of London)

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It's hard to comprehend the impact of the Black Death. The "Great Pestilence" is believed to have originated somewhere in Northern Asia in the 1330s before hitting Europe in 1347. It killed an estimated 75 million people worldwide - that's around 25 per cent of all humans in existence at the time. Now in an effort to better understand modern infectious diseases, scientist have sequenced the entire genome of the Black Death.

The research is based on analysis of skeletal remains from the East Smithfield "plague pits" in London using a previously developed methodology for extracting degraded DNA fragments of the bacteria that caused the plague - Yersinia pestis.

John Norden's map of London 1593

The international team, led by researchers from McMaster University and the University of Tubingen, say this is the first time a reconstructed genome of any ancient pathogen has been drafted.

So why is this relevant in the 21st Century?

Descendants of the specific variant of the Yersinia pestis found in the 14th Century remain exist today, killing an estimated 2,000 people a year. By drafting the reconstruction of the genome scientist are able to see changes in the pathogen's evolution - which in this case have been minor - and gain a better understanding of such deadly infections.

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

There are still questions that remain unanswered about why the Black Death was so devastating however.

"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."

In other words, the research may have knocked out one of the main contenders in establishing why the Black Death had such a deadly impact. The Paper states that because the Black Death may not have been due to bacterial phenotype, "factors other than microbial genetics, such as environment, vector dynamics and host susceptibility, should be at the forefront of epidemiological discussions regarding emerging Y. pestis infections."

It has also been shown that the variation of Yersinia pestis that caused the medieval plague originated sometime around the 12th Century, which means that it was not the cause of the Justinian plague that struck the Byzantine Empire around 540 CE was not caused by the same pathogen as once thought.

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

The research is published online in the scientific journal Nature

Source: McMaster University


Could this research possibly be stolen and weaponized? This would be a weapon of mass distruction!

15th October, 2011 @ 05:53 am PDT

It is pretty obvious what happened. The Black Death germ simply killed every human on the planet who was susceptible to it. The children who made up the next generation were all descended from parents who were naturally resistant.

That is a great example of the system called human evolution. It is a type of "tough love" deal that everyone admires but no one actually wants to participate in. We would all prefer to sit on the sidelines and watch.

Imagine if 25% of the people on the planet died from a single disease in our times! It would be almost two billion deaths.

15th October, 2011 @ 05:44 pm PDT

Smallpox is still deadly, even with the shots, it is locked up in labs to study, and a very great threat if it gets loose. If the Black Death simply used up all the susceptible hosts, then we would all be safe from then on. Not true. Germs mutate, strains drift, resistance means less likely or less deadly, but dead is still dead. Read a book, and learn something about antibiotics, and how they are loseing their effectiveness. There is nothing simple about it.

19th October, 2011 @ 07:52 pm PDT
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