An international team of scientists has discovered that two of the world’s most devastating plagues – the plague of Justinian and the Black Death, each responsible for killing as many as half the people in Europe — were caused by distinct Yersinia pestis strains, one that faded out on its own, the other leading to worldwide spread and re-emergence in the late 1800s. These findings suggest a new strain of plague could emerge again in humans in the future.
Burial of plague victims at the early medieval cemetery Aschheim. Foto: © H-P. Volpert
Fig. 2: Plague victim analyzed in the lab.
Using sophisticated methods, researchers from various institutions including McMaster University, State Collection of Anthropology and Paleoanatomy, Munich, Bundeswehr Institute of Microbiology, Munich, Northern Arizona University and the University of Sydney, isolated miniscule DNA fragments from the 1500-year-old teeth of two victims of the Justinian plague, buried in Bavaria, Germany. These are the oldest pathogen genomes obtained to date.
Using these short fragments, they reconstructed the genome of the oldest Yersinia pestis, the bacterium responsible for the plague, and compared it to a database of genomes of more than a hundred contemporary strains.
The results are currently published in the online edition of Lancet Infectious Disease. 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, for example why has this particular Y. pestis strain no genetic successors and died out?” questions Holger Scholz, head of the department of Bacteriology and Toxinology at the Bundeswehr Institute of Microbiology in Munich.The findings are dramatic because little has been known about the origins or cause of the Justinian Plague– which helped bring an end to the Eastern Roman Empire – and its relationship to the Black Death, some 800 years later.
The Plague of Justinian struck in the sixth century and is estimated to have killed between 30 and 50 million people— virtually half the world’s population as it spread across Asia, North Africa, Arabia and Europe. The Black Death would strike some 800 years later with similar force, killing 50 million Europeans between just 1347 and 1351 alone.
The third pandemic, which spread from Hong Kong across the globe is likely a descendant of the Black Death strain and thus much more successful than the one responsible for the Justinian Plague.
“We know the bacterium Y. pestis has jumped from rodents into humans throughout history and rodent reservoirs of plague still exist today in many parts of the world. If the Justinian plague could erupt in the human population, cause a massive pandemic, and then die out, it suggests it could happen again. Fortunately we now have antibiotics that could be used to effectively treat plague, which lessens the chances of another large scale human pandemic” says Dave Wagner, an associate professor in the Center for Microbial Genetics and Genomics at Northern Arizona University. However, we should not underestimate the devastating potential of plague, as in recent years strains emerged which are resistant to antibiotics, routinely used in plague therapy, adds Holger Scholz.
The samples used in the latest research were taken from two victims of the Justinian plague, buried in a gravesite in a small cemetery in the German town of Aschheim. The skeletal remains of the early medieval cemetery of Aschheim are examined by researchers of the Munich State Collection of Anthropology and Paleoanatomy since several years”, says Michaela Harbeck, curator of this institution which keeps ten thousands of skeletons, each of them an unique historical and biological source.The skeletal remains yielded important clues and raised more questions.
Researchers now believe the Justinian Y. pestis strain originated in Asia, not in Africa as originally thought.
“This study raises intriguing questions about why a pathogen that was both so successful and so deadly today only infects about 3000 people each year. From our genome analyses we know that Yersinia pestis from both the Black Death and the Justinian plague was not more dangerous than present Y. pestis strains, says Holger Scholz. One testable possibility is that human populations evolved to become less susceptible,” says Holmes. “Another possibility is that changes in the climate became less suitable for the plague bacterium to survive in the wild,” says Julia Riehm of the Bundeswehr Institut of Microbiology.
Scientists hope their research could lead to a better understanding of the dynamics of modern infectious disease, including a form of the plague that still kills thousands every year.
The research was funded in part by the Social Sciences and Humanities Research Council of Canada, Canada Research Chairs Program, U.S. Department of Homeland Security, U.S. National Institutes of Health and the Australian National Health and Medical Research Council.
For more information please contact:PD Dr. Holger C. Scholz
Team pinpoints genes that make plant stem cells, revealing origin of beefsteak tomatoes
26.05.2015 | Cold Spring Harbor Laboratory
DNA double helix does double duty in assembling arrays of nanoparticles
26.05.2015 | DOE/Brookhaven National Laboratory
The only professorship in Germany to date, one master's programme, one laboratory with worldwide unique equipment and the corresponding research results: The University of Würzburg is leading in the field of biofabrication.
Paul Dalton is presently the only professor of biofabrication in Germany. About a year ago, the Australian researcher relocated to the Würzburg department for...
Physicists have developed an innovative method that could enable the efficient use of nanocomponents in electronic circuits. To achieve this, they have developed a layout in which a nanocomponent is connected to two electrical conductors, which uncouple the electrical signal in a highly efficient manner. The scientists at the Department of Physics and the Swiss Nanoscience Institute at the University of Basel have published their results in the scientific journal “Nature Communications” together with their colleagues from ETH Zurich.
Electronic components are becoming smaller and smaller. Components measuring just a few nanometers – the size of around ten atoms – are already being produced...
Development and implementation of an advanced automobile parking navigation platform for parking services
To fulfill the requirements of the industry, PolyU researchers developed the Advanced Automobile Parking Navigation Platform, which includes smart devices,...
The world's first electrical car and passenger ferry powered by batteries has entered service in Norway. The ferry only uses 150 kWh per route, which...
On Tuesday, 19 May 2015 the research icebreaker Polarstern will leave its home port in Bremerhaven, setting a course for the Arctic. Led by Dr Ilka Peeken from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) a team of 53 researchers from 11 countries will investigate the effects of climate change in the Arctic, from the surface ice floes down to the seafloor.
RV Polarstern will enter the sea-ice zone north of Spitsbergen. Covering two shallow regions on their way to deeper waters, the scientists on board will focus...
20.05.2015 | Event News
18.05.2015 | Event News
12.05.2015 | Event News
27.05.2015 | Health and Medicine
26.05.2015 | Ecology, The Environment and Conservation
26.05.2015 | Life Sciences