Delving into the Diversity of The Plague of Justinian

Wayson stain of Yersinia pestis showing the characteristic
Yersinia pestis. U.S. Center for Disease Control [Public domain], via Wikimedia Commons.
Human teeth play a key role in our understanding of how organisms evolve. Whenever a possible new member of the hominid family is uncovered, the shape and number of teeth are used to place that individual in the family tree. Teeth also harbor information about pathogens that have plagued humans for millennia. Because bacteria use our bloodstream as a transport system, protected places that can preserve DNA—like the pulp of teeth—are a rich medium for uncovering information about humans and the microbes that infected them.

Teeth have been the choice for identifying the infectious agent behind the Plague of Justinian in the sixth century and the Black Plague in the 14th century. In fact, Yersinia pestis, the bacterium responsible for these plagues, has infected humans as far back as the Neolithic. But what can we learn about the pandemic strain or strains of Y. pestis described in historical records? A team of researchers from Europe and the US, many of whom have been delving into the history of Y. pestis for the last decade, wanted to further investigate the Plague of Justinian. They studied bacterial DNA extracted from human remains found in Western European communal graves that were dated to around 541–750, the period of the historically documented Plague of Justinian. Their investigation examined the bacteria’s diversity and how far it spread during this “First Pandemic” of plague. Continue reading “Delving into the Diversity of The Plague of Justinian”

Ancient Samples Confirm the Cause of the 6th Century Plague Pandemic

Yersinia pestis by A.Myasnikov for Wiki (Self made work) [CC0], via Wikimedia Commons
When I started writing about research on Yersinia pestis and the Black Death, I was amazed at the ability to recover 14th century bacterial DNA from human remains, show Y. pestis was the caustive agent of the Black Death and then sequence the strain to compare to modern Y. pestis strains. The publications I read always mentioned the three waves of pandemics that devastated human populations in the introduction, and the Black Death was not the oldest one. The putative first pandemic was the Plague of Justinian in the 6th century, named after the Byzantine emperor. Like with the Black Death, there is debate about whether Y. pestis is the causative agent of the Plague of Justinian. The research published in PLOS Pathogens built on earlier work to isolate and genotype the suspected Y. pestis causative agent from human remains in 6th century graves, but this time with more stringent protocols enacted to answer critics who questioned the authenticity of earlier results. Continue reading “Ancient Samples Confirm the Cause of the 6th Century Plague Pandemic”