Volume 25, Issue 1 p. 40-44
Editorial

The global virome: How much diversity and how many independent origins?

Eugene V. Koonin

Corresponding Author

Eugene V. Koonin

National Center for Biotechnology Information, National Library of Medicine, Bethesda, Maryland, USA

Correspondence

Eugene V. Koonin, National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD, USA.

Email: [email protected]

Mart Krupovic, Institut Pasteur, Université Paris Cité, CNRS UMR6047, Archaeal Virology Unit, Paris, France.

Email: [email protected]

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Mart Krupovic

Corresponding Author

Mart Krupovic

Institut Pasteur, Université Paris Cité, CNRS UMR6047, Archaeal Virology Unit, Paris, France

Correspondence

Eugene V. Koonin, National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD, USA.

Email: [email protected]

Mart Krupovic, Institut Pasteur, Université Paris Cité, CNRS UMR6047, Archaeal Virology Unit, Paris, France.

Email: [email protected]

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Valerian V. Dolja

Valerian V. Dolja

Department of Botany and Plant Pathology, Oregon State University, Oregon, USA

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First published: 12 September 2022
Citations: 10

Funding information: National Institutes of Health

Abstract

Viruses are considered to be the most abundant biological entities on earth. They also display striking genetic diversity as emphatically demonstrated by the recent advances of metagenomics and metatranscriptomics. But what are the limits of this diversity, that is, how many virus species in the earth virome? By combining the available estimates of the number of prokaryote species with those of the virome size, we obtain back-of-the-envelope estimates of the total number of distinct virus species, which come out astronomically large, from about 107 to about 109. The route of virus origins apparently involved non-viral replicators capturing and exapting various cellular proteins to become virus capsid subunits. How many times in the history of life has this happened? In other words, how many realms of viruses, the highest rank taxa that are supposed to be monophyletic, comprise the global virome? We argue that viruses emerged on a number (even if far from astronomical) independent occasions, so the number of realms will considerably increase from the current 6, by splitting some of the current realms, giving the realm status to some of the currently unclassified groups of viruses and discovery of new distinct groups.

CONFLICT OF INTEREST

The authors report no competing interests.