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Viruses 2017, 9(10), 276;

Comment: Characterization of Two Historic Smallpox Specimens from a Czech Museum

Marie Bashir Institute for Infectious Diseases and Biosecurity, Charles Perkins Centre, School of Life and Environmental Sciences and Sydney Medical School, The University of Sydney, Sydney, NSW 2006, Australia
McMaster Ancient DNA Centre, Department of Anthropology, McMaster University, Hamilton, ON L8S 4L9, Canada
Michael G. DeGroote Institute for Infectious Disease Research and the Department of Biochemistry, McMaster University, Hamilton, ON L8S 4L8, Canada
Author to whom correspondence should be addressed.
Received: 31 August 2017 / Revised: 25 September 2017 / Accepted: 25 September 2017 / Published: 28 September 2017
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The complete genome sequences of two strains of variola virus (VARV) sampled from human smallpox specimens present in the Czech National Museum, Prague, were recently determined, with one of the sequences estimated to date to the mid-19th century. Using molecular clock methods, the authors of this study go on to infer that the currently available strains of VARV share an older common ancestor, at around 1350 AD, than some recent estimates based on other archival human samples. Herein, we show that the two Czech strains exhibit anomalous branch lengths given their proposed age, and by assuming a constant rate of evolutionary change across the rest of the VARV phylogeny estimate that their true age in fact lies between 1918 and 1937. We therefore suggest that the age of the common ancestor of currently available VARV genomes most likely dates to late 16th and early 17th centuries and not ~1350 AD. View Full-Text
Keywords: smallpox; variola virus; evolution; ancient DNA; molecular clock; phylogeny smallpox; variola virus; evolution; ancient DNA; molecular clock; phylogeny

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Porter, A.F.; Duggan, A.T.; Poinar, H.N.; Holmes, E.C. Comment: Characterization of Two Historic Smallpox Specimens from a Czech Museum. Viruses 2017, 9, 276.

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