By Medical Discovery News
April 14, 2012
Underneath the heart of London’s financial district and the Royal Mint lay the remains of East Smithfield Cemetery. There lie some 2,400 bodies, each carefully laid to rest facing east to west with layers of charcoal in between. Around many bodies are trinkets revealing the lives they once had.
Within five years, the Black Death took the lives of these victims, as well as 30 to 60 percent of not only London’s population but Europe’s.
Now East Smithfield, one of only a few known cemeteries to contain victims of the Black Death, has provided scientists with crucial material to confirm the bacterium Yersinia pestis caused the Bubonic Plague, and allowed them to identify the microbe’s genome.
This adds to an old debate among scientists. Doubts over cause of this pandemic have perpetuated because today’s plague infects and kills far fewer people and with different symptoms. Scientists believed having the full genetic sequence of the 14th century strain would help them understand what made it so deadly.
The research team, led by Kirsten I. Bos of McMaster University in Ontario and Johannes Krause of the University of Tübingen in Germany, focused their work on samples of dental pulp, the innermost layer of tissue in teeth, where they were able to extract, purify and enrich the Yersinia genetic information.
Using a technique called targeted capture, they used lab-synthesized “bait” DNA to snag ancient Yersinia DNA strands, leaving soil microbes and other material behind. Then with the newest generation of DNA sequencers, they read snippets of the nearly 700-year-old microbe. It’s the first time an ancient microbe has been reconstructed after taken human remains, opening the way for scientists to identify microbial genomes that caused other major epidemics.
McMaster’s team found the ancient strain to be remarkably similar to today’s plague, which means it’s no deadlier and can be controlled by antibiotics. This leads researchers to conclude that climate, age distribution and living conditions of 14th century Europe contributed to the pandemic.
In 1348, downtown London was densely packed and filthy, the climate was wet and cold, and food was in short supply. People also did not have antibiotics like they do today. Understanding how the microbe exploits different conditions can help preparations for future outbreaks.
Researchers also plan to use the genomic information to recreate the original microbe. While this will help scientists understand the bacterium even further, it’s also a security risk. Yersinia has been weaponized by a number of groups in the past. Scientists face an ethical dilemma as they consider how their work, if published, may be misused.
Today, Yersinia strains sicken about 3,000 people around the world every year. However, with antibiotics, 85 percent of people recover, reinforcing the power of modern medical capabilities.
Pamela K. Bond 