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Ancient Treponema pallidum from human remains sheds light on its evolutionary history

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IMAGE: Examples for bone lesions for the three positively diagnosed individuals. Skeletal collection from Santa Isabel Convent, Mexico City, in custody of the Laboratory of Osteology, Post Graduate Studies Division, National... view more 

Credit: Krause et al, 2018

The evolutionary history and origin of syphilis, and other treponemal diseases, is a hotly debated topic by scholars. Scholars who theorize syphilis originated in the "New World" and preceded the 15th century have been in fierce debate with scholars who theorize a multiregional origin followed by the 15th century pandemic spread. Both sides are supported by organic evidence found in contemporary genetic and skeletal remains across the globe.

In their new research article published with PLOS Neglected Tropical Diseases, Dr. Johannes Krause of the Max Planck Institute for the Science of Human History along with his colleagues, contribute to this long-lasting debate by examining the human remains of Post-Columbian period individual. Skeletons that displayed signs of infection in the form of mended bone fractures and bone tumors were selected to have their genomes analyzed and compared to ancient genomes of Treponema pallidum.

Their findings reveal that both reconstructed sub-species of T. pallidum genomes, T. pallium ssp. pallidum (associated with syphilis in infants) and T. pallium ssp. pertenue (the causative agent of yaws) can show similar symptoms. Their similar symptoms provide strong evidence for the rearrangement of this ancient DNA. Although the individuals included in the study present skeletal changes consistent with treponematosis, the researchers were unable to visually differentiate between the genomes due to the shared signs of yaws and syphilis and the varying degrees of skeletal preservation. The limited resolution of diagnosis compromised the ability of these researchers to visualize a diagnosis through the pathological changes in the remains. However, their testing did successfully identify syphilis infection in two individuals, syphilis in one individual, and yaws in one infant.

"Our work demonstrates the value of molecular identification of ancient pathogens, particularly as applied to treponemal diseases where skeletal responses to the various pathogenic subspecies are often shared, challenging the development of a confident diagnosis through osteological observation," the researchers note. "Previous research that found the presence of T. pallidum ssp. pertenue in old world monkeys, and our finding that two T. pallidum subspecies likely caused similar skeletal manifestations in the past, may suggest a more complex evolutionary history of T. pallidum than previously assumed."

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In your coverage please use this URL to provide access to the freely available article in PLOS Neglected Tropical Diseases: http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0006447

Citation: Schuenemann VJ, Kumar Lankapalli A, Barquera R, Nelson EA, Iraíz Hernández D, et al. (2018) Historic Treponema pallidum genomes from Colonial Mexico retrieved from archaeological remains. PLOS Neglected Tropical Diseases 12(6): e0006447. https://doi.org/10.1371/journal.pntd.0006447

Funding: This work was supported by the Max Planck Society (J.K.) and the European Research Council (ERC) starting grant APGREID (J.K.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing Interests: The authors have declared that no competing interests exist.

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