A group of researchers from Kiel University and the Max Planck Institute of Evolutionary Biology (MPI-EB) have conducted a study on the genetic factors that the plague pathogen Yersinia pestis acquired during its recent evolution. By examining ancient and modern Y. pestis genomes, the researchers found that the pathogen acquired a new genetic element, known as the YpfΦ prophage, between the late Middle Ages and the modern pandemic. This genetic element is related to the virulence of the pathogen, which affects its disease-causing ability.
The plague has a long history, with the earliest evidence of Y. pestis dating back approximately 5000 years. Notable outbreaks include the late antique Justinianic plague in the sixth century and the infamous Black Death in the late Middle Ages, both of which resulted in significant population declines in Europe. However, the most significant plague pandemic occurred from the mid-19th to the early 20th century, affecting Asia and subsequently spreading globally. This pandemic caused around 15 million deaths and continues to affect certain regions today.
The researchers obtained genetic samples from skeletal remains found in Danish parish cemeteries. These remains dated back to the 11th to 16th centuries. By comparing the Y. pestis genes in these samples with other published genomes, the researchers discovered that all known Y. pestis strains before the 19th century lacked the YpfΦ prophage. The acquisition of this genetic element likely took place through lateral gene transfer, allowing the pathogen to increase its virulence.
The researchers also identified a protein in the YpfΦ prophage that resembles toxins found in other pathogens, such as the cholera pathogen. This protein may contribute to the increased virulence of Y. pestis by facilitating the exchange of harmful substances between infected cells and damaging mucosa and epithelia. Further research is needed to investigate this protein and its role in the virulence of the plague pathogen.
Understanding the evolution of the plague pathogen is crucial for detecting new forms of the disease and preventing future pandemics. The rapid evolution of Y. pestis poses a continuous threat, as new genetic elements can lead to new symptoms of infection and antibiotic resistance. The study highlights the importance of studying historical disease evolution using ancient DNA to gain knowledge for modern science and medical applications.
In conclusion, the study conducted by researchers from Kiel University and MPI-EB has provided insights into the genetic factors acquired by Yersinia pestis during its recent evolution. The acquisition of the YpfΦ prophage has been linked to the increased virulence of the pathogen, shedding light on the emergence of the modern plague pandemic. Further research is necessary to understand the mechanisms behind this increased virulence and to prevent future pandemics.