Geneticists have decoded the genome of the plague bacillus, a bacterium that devastated Europe in the 14th century. It turned out that the deadly plague stick is almost indistinguishable from its harmless “great-grandmother”
In August 2011, scientists from universities in the USA, Germany and Canada, led by Johannes Krause of the University of Tuebingen, obtained the first partial data on the DNA of the plague bacillus Yersinia pestis, which killed 30 million people in one five-year period of the 14th century. … To do this, geneticists studied the bones and teeth of plague victims buried in 1348 in London's East Smithfield Cemetery.
In an August paper, researchers recovered circular DNA that is located outside the chromosomes and is needed by bacteria to synthesize proteins that suppress human immunity. This DNA - plasmid pPCP1 - biologists compared with similar parts of the genome in modern plague sticks, after which they came to the conclusion that the plague bacillus of the 14th century died out, leaving no descendants.
In the latest study, the results of which appeared in Nature, Dr. Krause and his colleagues used an already established technique to assemble the complete genome of Yersinia pestis.
They selected several well-preserved teeth from East Smithfield graves. The remains of the bacterial genome were found on the crowns and roots of teeth. The puzzle of four million nucleotides of genetics was assembled using a computer program.
As the researchers note, the accuracy of decoding the Yersinia pestis genome is high - comparable to the accuracy of decoding the human genome.
True, in the genome of the deadly bacterium there are still white spots: biologists have restored 93.5% of the genetic "puzzle" - the remaining parts have dissolved in the mass grave of East Smithfield.
Great-grandmother of the Black Death
Dr. Krause's team compared the structure of the resulting DNA with the genome of the modern plague bacillus (strain CO92). It turned out that most of the genes in chromosomes and plasmids coincide, but some regions are either completely absent in modern bacteria or are replaced by other DNA sequences.
Promotional video:
In the genome of a medieval bacterium, scientists have also discovered genes that combine the most ancient strains of Yersinia pestis with their common ancestor , the bacterium Yersinia pseudotuberculosis.
"This indicates that the genome of Yersinia pestis has changed little over the past 600 years, despite several epidemics and active person combat pathogens," - scientists say, summing up the results of the comparative analysis.
