Scientists have sequenced the entire genome of the bacterium that caused the Black Death, a bubonic plague that killed 50 million Europeans between 1347 and 1351 and ranks as one of the worst epidemics in human history.
The DNA of the specific variant of the Yersinia pestis bacterium was collected from the dental pulp of the skeletons of five people buried in plague pits in London.
This is the first time an ancient pathogen's genome has been sequenced, and the work could help improve knowledge about modern infectious diseases, according to researchers at McMaster University in Canada and colleagues in Germany and the United States.
"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," Hendrik Poinar, director of the McMaster Ancient DNA Centre and an investigator with McMaster's Michael G. DeGroote Institute of Infectious Disease Research, said in a university news release.
"With a better understanding of the evolution of this deadly pathogen, we are entering a new era of research into infectious disease," he added.
The research appears online Oct. 12 in the journal Nature.
The direct descendants of the bacterium that caused the Black Death still exist and cause about 2,000 deaths worldwide 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," Poinar said. "The next step is to determine why this was so deadly."
The same technique used to sequence the genome of the Black Death bacterium should also work on other pathogens from the past, which could help improve understanding about the evolution of human pathogens and historical pandemics, according to the researchers.
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