Ancient and Modern Leprosy Bacterial Genomes Offer Insights into Disease History

From skeletons and biopsies, an international team of scientists has been successful in reconstructing a dozen medieval and modern genomes of the leprosy-causing bacteria Mycobacterium leprae. Under the direction of Professor Johannes Krause, University of Tübingen, and Professor Stewart Cole, Swiss Federal Institute of Technology of Lausanne (EPFL), the research group created a genome from archaeological finds for the first time without having to resort to a reference sequence. Professor Almut Nebel and Dr. Ben Krause-Kyora, both of the Institute of Clinical Molecular Biology, Kiel University, belong to the team, whose findings were published online on June 13, 2013 in Science magazine. Leprosy, a devastating infectious and chronic disease, was widespread in Europe until the Late Middle Ages. Persons infected with the disease were isolated in leprosy colonies specifically built for the patients. Today, the disease is found in 91 countries worldwide with more than 200,000 new infections per year. In order to trace the history of the disease, the scientists reconstructed the complete genomes of M. leprae from five medieval skeletons from Denmark, Sweden, and Great Britain. These specimens exhibited the characteristic bone changes associated with leprosy. Additionally, the M. leprae genetic substance was decoded from seven biopsy samples of contemporary patients. The researchers compared the European medieval M. leprae genome with those of the seven biopsies and four additional modern bacteria strains. They observed that all M. leprae strains have a common ancestor that existed less than 4,000 years ago. This result is supported by the earliest archaeological evidence of the disease in India.
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