Thanks to a 200-year-old mummy, researchers were able to recover uncontaminated tuberculosis genomes from its lung tissue. Using a technique known as metagenomics, scientists are calling it a breakthrough.
The mummy was found to be precisely 215 years old after scientists discovered the remains came from a Hungarian woman, Terézia Hausmann, who died at the age of 28 on Dec. 25, 1797. Her mummified body was discovered in a crypt in Vác, Hungary, about 40 miles north of Budapest. The crypt, which was opened in 1994, had 242 other naturally mummified bodies, researchers said.
“Most other attempts to recover DNA sequences from historical or ancient samples have suffered from the risk of contamination, because they rely on amplification of DNA in the laboratory, Mark Pallen, a professor of Microbial Genomics at Warwick Medical School in the United Kingdom, said in a statement. “The beauty of metagenomics is that it provides a simple but highly informative, assumption-free, one-size-fits-all approach that works in a wide variety of contexts.”
Metagenomics involves collecting genetic material from a mixed community of organisms. The open-ended DNA sequencing also doesn’t need “culture or target-specific amplification or enrichment.
Although an X-ray of Hausmann’s body showed no signs of the infection, a molecular analysis of a chest sample confirmed she had tuberculosis. Not only that -- the sample was an “extremely good preservation of mycobacterial DNA,” the study’s authors wrote.
The findings published in the New England Journal of Medicine showed that Hausmann suffered from a mixed infection drawn from two different strains of the tuberculosis bacteria. The strain strongly resembled a tuberculosis outbreak that took place in Germany from 1998 to 2010.
“In this case, metagenomes revealed that some strain lineages have been circulating in Europe for more than two centuries,” Pallen said about the infection that has lasted for hundreds of years.
Tuberculosis is caused by a bacterium that usually attacks the lungs. The infection is spread through the air from coughs and sneezes. TB infections started to increase in number after the emergence of HIV in 1985. Today, the infection is the leading killer of people with HIV with one third of the world’s population infected, according to the U.S. Center for Disease Control.
“It was fascinating to see the similarities between the TB genome sequences we recovered and the genome of a recent outbreak strain in Germany. It shows once more that using metagenomics can be remarkably effective in tracking the evolution and spread of microbes without the need for culture,” Pallen said.