Seeking to understand more about the origins and movement of bubonic plague, in ancient and contemporary times, researchers at McMaster University, the University of Sydney and the University of Melbourne have completed a close examination of hundreds of modern and ancient genome sequences, creating the largest analysis of its kind.
Despite huge advances in DNA technology and analysis, the origin, evolution, and spread of plague remains difficult to determine.
The plague is responsible for the two largest and deadliest epidemics in human history. However, the ebb and flow of these factors, and why some die and others persist for years, have confused scientists.
In a paper published today in the journal Communication biologyMcMaster researchers use extensive data and analysis to plot what they can about a highly complex history Y. pestis, The bacteria that cause plague.
The research features analysis of more than 600 genome sequences from around the world, encompassing the first appearance of plague in humans 5,000 years ago, the Justinian plague, the medieval Black Death and the current (or third) plague, which began as early as 2000. 20y century.
“The plague was the largest pandemic and the greatest fatality event in human history. When it appeared and from what host may shed light on where it came from, why it continued to erupt over hundreds of years and faded in some places and persisted in others. And, in the end, why it killed so many people people,” explains evolutionary geneticist Hendrik Poinar, director of the Center for Ancient DNA at McMaster.
Poinar is a principal investigator at the Michael G. DeGroote Institute for Infectious Disease Research and McMaster’s Global Nexus for Pandemics & Biological Threats.
The team studied and determined the genomes of strains distributed around the world and of different ages Y. pestis He has an unstable molecular clock. This makes it particularly difficult to measure the rate at which mutations accumulate in their genome over time, which are then used to calculate dates of emergence.
Because Y. pestis It develops at a very slow pace, it is almost impossible to say exactly where it originated.
Humans and rodents carried the pathogen around the world through travel and trade, allowing it to spread faster than its genome evolved. Genome sequences found in Russia, Spain, England, Italy and Turkey, although separated by years, are all identical, for example, creating enormous challenges for determining the path of transmission.
To address the problem, researchers have developed a new method for distinguishing between specific populations Y. pestisenabling them to identify and date five populations throughout history, including the most famous ancient pandemic strains that they now estimate emerged decades or even centuries before pandemics were historically documented in Europe.
“You can’t think of plague as just one bacterium,” Poinar explains. “Context is very important, which is shown by our data and analytics.”
To properly reconstruct epidemics from our past, present, and future, the historical, ecological, ecological, and sociocultural contexts are equally important.
It shows that genetic evidence alone is not sufficient to reconstruct the timing and spread of short-term plague epidemics, which has implications for future research related to past epidemics and the evolution of ongoing outbreaks such as COVID-19.