Implementation of objective PASC-derived taxon demarcation criteria for official classification of filoviruses

Yīmíng Bào, Gaya K. Amarasinghe, Christopher F. Basler, Sina Bavari, Alexander Bukreyev, Kartik Chandran, Olga Dolnik, John M. Dye, Hideki Ebihara, Pierre Formenty, Roger Hewson, Gary P. Kobinger, Eric M. Leroy, Elke Mühlberger, Sergey V. Netesov, Jean L. Patterson, Janusz T. Paweska, Sophie J. Smither, Ayato Takada, Jonathan S. TownerViktor E. Volchkov, Victoria Wahl-Jensen, Jens H. Kuhn*

*Corresponding author for this work

Research output: Contribution to journalLetterpeer-review

14 Citations (Scopus)


The mononegaviral family Filoviridae has eight members assigned to three genera and seven species. Until now, genus and species demarcation were based on arbitrarily chosen filovirus genome sequence divergence values (≈50% for genera, ≈30% for species) and arbitrarily chosen phenotypic virus or virion characteristics. Here we report filovirus genome sequence-based taxon demarcation criteria using the publicly accessible PAirwise Sequencing Comparison (PASC) tool of the US National Center for Biotechnology Information (Bethesda, MD, USA). Comparison of all available filovirus genomes in GenBank using PASC revealed optimal genus demarcation at the 55-58% sequence diversity threshold range for genera and at the 23-36% sequence diversity threshold range for species. Because these thresholds do not change the current official filovirus classification, these values are now implemented as filovirus taxon demarcation criteria that may solely be used for filovirus classification in case additional data are absent. A near-complete, coding-complete, or complete filovirus genome sequence will now be required to allow official classification of any novel “filovirus.” Classification of filoviruses into existing taxa or determining the need for novel taxa is now straightforward and could even become automated using a presented algorithm/flowchart rooted in RefSeq (type) sequences.

Original languageEnglish
Article number106
Issue number5
Publication statusPublished - 11 May 2017

Bibliographical note

Funding Information:
We thank Laura Bollinger and Jiro Wada (U.S. National Institutes of Health and National Institute of Allergy and Infectious Diseases (NIH/NIAID) Integrated Research Facility at Fort Detrick, Frederick, MD, USA) for critically editing the manuscript and figure creation, respectively. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the US Department of the Army, the U.S. Department of Defense, the U.S. Department of Health and Human Services, the Department of Homeland Security (DHS) Science and Technology Directorate (S&T), or of the institutions and companies affiliated with the authors. In no event shall any of these entities have any responsibility or liability for any use, misuse, inability to use, or reliance upon the information contained herein. The U.S. departments do not endorse any products or commercial services mentioned in this publication. This work was supported in part through Battelle Memorial Institute’s prime contract with the U.S. NIAID under Contract No. HHSN272200700016I. A subcontractor to Battelle Memorial Institute who performed this work is: J.H.K., an employee of Tunnell Government Services, Inc. This work was also supported in part by the 100 Talent Program of the Chinese Academy of Sciences (Y.B.). This work was also funded in part under Contract No. HSHQDC-15-C-00064 awarded by DHS S&T for the management and operation of the National Biodefense Analysis and Countermeasures Center (NBACC), a Federally Funded Research and Development Center (V.W.-J.).

Publisher Copyright:
© 2017 by the authors. Licensee MDPI, Basel, Switzerland.


  • Cuevavirus
  • Ebola
  • Ebolavirus
  • Filoviridae
  • Filovirus
  • ICTV
  • Marburgvirus
  • Mononegavirales
  • Virus classification
  • Virus taxonomy


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