A recent study published in the Proceedings Of The Royal Society B: Biological Sciences sheds light on the evolution of the ancient plague bacterium Yersinia pestis. The research paper titled “Ancient Yersinia pestis genomes lack the virulence-associated YpfΦ prophage present in modern pandemic strains” sheds light on the missing link between the ancient and modern strains of Yersinia pestis.
HISTORY OF YERSINIA PESTIS, THE BLACK PLAGUE:
Research reveals that Y. pestis an ancient plague, is believed to have caused numerous pandemics, epidemics, and endemics right from the beginning of the Neolithic age. Studies suggest that it was contained to Asia, mainly India, and China then spread globally due to trade after its inception. It was the causative agent of the Black Death that nearly decimated Europe in the 14th century, killing an estimated 20 million people and causing the Dark Ages of Europe.
The most recent case of the plague outbreak was seen in April 2022 in the Democratic Republic of Congo which lead to mass migration and spread of cases.
UNDERSTANDING THE BLACK DEATH
The research team led by Dr. Daniel Unterweger, research group leader at the MPI-EB (Max Planck Institute for Evolutionary Biology) and Kiel University, along with Professors Almut Nebel and Ben Krause-Kyora from the Institute of Clinical Molecular Biology (IKMB) at Kiel University examined many different strains of Y. pestis ranging from ancient strains to modern-day strains. They hypothesized that Y. pestis had integrated a prophage YpfΦ that conferred it with enhanced infectious properties.
The research group collaborated with the Department of Forensic Medicine at SDU (South Denmark), and obtained 40 samples from two medieval cemeteries in Denmark: Sct Trinitatis/Drotten in Viborg and Ødekirkegård in Sejet.
By sequencing the genomes of Y. pestis strains from remains dating back thousands of years, the team compared them with modern pandemic strains, aiming to identify genetic variations that may have contributed to the Y. pestis increased virulence.
The researchers discovered that the ancient Y. pestis genomes lacked the YpfΦ prophage entirely. This crucial absence suggests the possibility that ancient strains may not have possessed the same level and degree of virulence as their modern counterparts, despite the ancient strains causing significant historical pandemics.
Protein analysis suggested that the protein generated by the YpfΦ gene has some structural homology to the Zonula occludens toxin (Zot) protein seen in Vibrio cholerae an enterotoxin that helps the bacteria invade intestinal cells by negatively affecting the cell junctions.
HIGHLIGHTSÂ OF THE STUDY
This groundbreaking study serves as a testament to the power of ancient DNA analysis in unraveling mysteries of the past and provides vital insights into the evolution of one of history’s most notorious pathogens.
The study highlights the importance of understanding the role bacteriophages (viruses that infect bacteria) play in shaping the evolution of pathogenic bacteria.
Bacteriophages facilitate the transfer of genes between different bacterial species, including virulence genes, possibly further altering the disease-causing capabilities of these bacteria. Y. pestis has acquired many such genes responsible for their increased virulence capabilities, due to genetic transfer study shows.
Future research is needed to investigate the precise mechanisms that underlie the process of acquisition and spread of the YpfΦ prophage among Y. pestis strains.
In addition, investigating other genetic elements and environmental factors that may have contributed to the evolution of Y. pestis will be crucial to gaining an exhaustive and detailed account of the bacterium’s history.
By understanding the genetic changes that underlie Y. pestis‘ virulence, scientists are better able to prepare for and mitigate the potential impact of future outbreaks, ultimately safeguarding public health.
