Researchers detected DNA of the plague bacterium in 1500 year-old skeletons
Scientists of the Bavarian State Collection for Anthropology and Paleoanatomy, Ludwig Maximilians University and the Bundeswehr Institute of Microbiology, Munich succeeded in the molecular analysis of Yersinia pestis in 1500 years-old skeletons. With the support from American bioforensic and molecular typing specialists at the Northern Arizona University, and a second ancient DNA team from the Gutenberg University, Mainz, the results could be confirmed and published in PLOS Pathogens. It is now conclusively shown that Yersinia pestis infected the human population of Bavaria already in the 6th century.
Since several years, researchers of the Ludwig Maximilians University, Munich investigated the early medieval graveyard of Aschheim-Bajuwarenring (500 -700 AD) comprising a total of 402 graves. “Unusually, there were several multiple burials with up to six individuals in one grave” stated Dr. Michaela Harbeck, the leader of the study. Associated historical reports about epidemics at the time of the emperor Justinian arouse the suspicion of potential plague victims.
Using molecular methods, the researchers detected the plague bacterium in 8 out of 19 skeletal remains. The presence of Y. pestis in the tooth pulp suggests that the victims suffered from septicemia, one of the most severe and lethal clinical form of the disease. During septicemic infection, thousands of bacteria are present in every milliliter of blood. After death, the bacterial DNA can be preserved in residues of small blood vessels in the protective environment of the tooth pulp for centuries. Molecular assays for the detection of Y. pestis were developed at the German Bundeswehr Institute of Mircobiology. “We design assays and validate those according to the international standard ISO15189” says Dr. Julia Riehm, “tThis is very important to detect low amounts of DNA”.
Using highly sensitive molecular methods, the researchers could further characterize one sample at the genetic level. “This is extremely important in order to obtain a better understanding about the history of the plague bacterium and the origin and spread of pandemics”, explains Dr. Holger Scholz.
“We found an old progenitor of the modern plague bacterium”, explained Lisa Seifert, a PhD student who carried out the molecular analysis. “It is definitively older than Y. pestis causing the Black Death in the Middle Ages.” The phylogeographic analysis suggests an origin of the Justinian Plague in Central Asia, although previous historical reports pointed to Africa as the potential origin.
Despite this important finding, further research is necessary to answer the question whether the Justinian Plague was caused by a single strain from a single origin or whether multiple strains were imported in several waves from different continents.
Harbeck M, Seifert L, Hänsch S, Wagner DM, Birdsell D, et al. (2013) Yersinia pestis DNA from Skeletal Remains from the 6th Century AD Reveals Insights into Justinianic Plague. PLoS Pathog 9(5): e1003349. doi:10.1371/journal.ppat.1003349
Dr. Michaela Harbeck
Dipl. Biol. Lisa Seifert
Staatssammlung für Anthropologie und Paläoanatomie
Lisa Seifert: +49-1719764963
Dr. Holger C. Scholz
Mikrobiologisches Institut der Bundeswehr