The team reconstructed the genome of the oldest strain of Yersinia pestis, the bacterium responsible for the bubonic plague, and compared it to a database of genomes of more than one hundred contemporary strains.
The results are currently published in the online edition of The Lancet Infectious Diseases. They show the strain responsible for the Justinian outbreak was an evolutionary 'dead-end' and distinct from strains involved later in the Black Death and other plague pandemics that would follow.
"The research is both fascinating and perplexing, it generates new questions which need to be explored," said Hendrik Poinar, associate professor and director of the McMaster Ancient DNA Centre and an investigator with the Michael G. DeGroote Institute for Infectious Disease Research. "For example, why did this pandemic, which killed somewhere between 50 and 100 million people, die out?"
The third pandemic, which spread from Hong Kong across the globeincluding all the way to Arizonais likely a descendant of the Black Death strain and thus was much more successful in evolutionary terms than the one responsible for the Justinian plague.
Although the rise and fall of the Justinian plague suggests that a similar emergence could happen again with a new strain, other factors render the scenario unlikely, Wagner said.
"We don't think we're going to see new large-scale plague pandemics. Not because the organism has changedit's just as deadly as it always wasbut humans have changed," Wagner
|Contact: Eric Dieterle|
Northern Arizona University