Date Published: May 2, 2013
Publisher: Public Library of Science
Author(s): Michaela Harbeck, Lisa Seifert, Stephanie Hänsch, David M. Wagner, Dawn Birdsell, Katy L. Parise, Ingrid Wiechmann, Gisela Grupe, Astrid Thomas, Paul Keim, Lothar Zöller, Barbara Bramanti, Julia M. Riehm, Holger C. Scholz, Nora J. Besansky.
Yersinia pestis, the etiologic agent of the disease plague, has been implicated in three historical pandemics. These include the third pandemic of the 19th and 20th centuries, during which plague was spread around the world, and the second pandemic of the 14th–17th centuries, which included the infamous epidemic known as the Black Death. Previous studies have confirmed that Y. pestis caused these two more recent pandemics. However, a highly spirited debate still continues as to whether Y. pestis caused the so-called Justinianic Plague of the 6th–8th centuries AD. By analyzing ancient DNA in two independent ancient DNA laboratories, we confirmed unambiguously the presence of Y. pestis DNA in human skeletal remains from an Early Medieval cemetery. In addition, we narrowed the phylogenetic position of the responsible strain down to major branch 0 on the Y. pestis phylogeny, specifically between nodes N03 and N05. Our findings confirm that Y. pestis was responsible for the Justinianic Plague, which should end the controversy regarding the etiology of this pandemic. The first genotype of a Y. pestis strain that caused the Late Antique plague provides important information about the history of the plague bacillus and suggests that the first pandemic also originated in Asia, similar to the other two plague pandemics.
In 541 AD, eight centuries before the Black Death, a deadly infectious disease hit the Byzantine Empire, reaching Constantinople in 542 and North Africa, Italy, Spain, and the French-German border by winter 543 . The so called “Plague of Justinian”, named after the contemporaneous emperor, led to mass mortality in Europe similar to that of the Black Death. It persisted in the territory of the Roman Empire until the middle of the 8th century and likely contributed to its decline, shaping the end of antiquity . Based on historical records, this disease has been diagnosed as bubonic plague although discrepancies between historical sources and the progression of Y. pestis infections have led some authors to suppose that the Plague of Justinian was caused by a different pathogen (as discussed in ). This vivacious discussion was recently reinforced by an ancient DNA study of the second pandemic that also questioned whether Y. pestis was truly the causative agent of the first pandemic , .
Our analyses conducted in two separate aDNA laboratories independently confirmed our previous results  that some humans buried in the 6th century Ascheim cemetery were infected with Y. pestis. These findings confirm that Y. pestis was the causative agent of the Justinianic Plague and should end the controversy over the etiological agent of the first plague pandemic. This outcome is contrary to a recent study  that questioned whether Y. pestis was indeed the causative agent of the first pandemic based upon the assumption that only strains from major branches one and two are pathogenic to humans, which they estimated to have emerged only in the 13th century AD. However, Cui et al.  recently determined that most Y. pestis lineages are capable of causing human plague and suggested that this capability has been present since Y. pestis evolved from its Y. pseudotuberculosis ancestor approximately 1,500–6,400 years ago. Thus, they concluded that Y. pestis strains pathogenic to humans already existed long before the beginning of the first pandemic.