Black Death Genome Sequence Completed: Why It’s Important

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The genome of the bacterium that caused the Black Death, an extremely deadly epidemic that killed 30 to 50% of the European population between 1347 and 1351, has been sequenced by an international team of scientists. Nearly 700 years later, why is it important to understand the pathogen that eliminated 50 million people?

Understanding the Black Death is important today

The story of the Black Death (bubonic plague) has fascinated historians, scientists, and the general public alike for centuries. Adding to the fascination is recent work by investigators involved in the genome sequencing project, who extracted specimens from the skeletons of Black Death victims in the East Smithfield “plague pits” in London, an area noted in historical data as a burial ground for people who died of the plague.

The scientists screened 46 teeth and 53 bones from the East Smithfield collection for the pathogen. Using samples taken from the dental pulp of five plague victims, they were able to isolate DNA from the causative agent, a specific variant of Yersinia pestis, Y. pestis-specific pPCP1.

According to one of the investigators, geneticist Hendrik Poinar from McMaster University in Canada, “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.”

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Although we don’t hear much about plagues today, an estimated 2,000 people die each year from pathogens that are direct descendants of the bubonic plague. The bubonic plague, which is transmitted from animals to people mainly via rodents and the fleas that infest them, typically kills two-thirds of its victims within four days if they are not treated.

Sequencing the genome of the Black Death will allow scientists to examine how the pathogen evolved over the centuries, contribute to their understanding of infectious diseases today, and hopefully lead to more effective ways to prevent, diagnose, and treat them.

In addition, scientists can now employ the same methodology used in this sequencing project to study the genomes of other historic pathogens, which may provide even more insights into pandemics. The authors noted that “genetic data from ancient infectious diseases will provide invaluable contributions towards our understanding of host-pathogen coevolution.”

SOURCE:
Bos KI et al. Nature 2011 Oct 12 online; doi:10.1038/nature10549

Picture credit: Wikimedia Commons

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