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What makes a virus a virus: reply from Raoult and Forterre

Nature Reviews Microbiology volume 6, page 643 (2008)Cite this article

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The correspondence on our Opinion article (Redefining viruses: lessons from mimivirus. Nature Rev. Microbiol. 6, 315–319 (2008)1) by Wolkowicz and Schaechter (What makes a virus a virus? Nature Rev. Microbiol. 16 July 2008 (doi:10.1038/nrmicro1858-c1)2) has allowed us to clarify some of the elements of our virus definition1. The authors rightly insist that the phenomenon of disappearance and reappearance of a virus (eclipse phase) is a major characteristic of viruses. They then go a step further, however, to suggest that it is the most fundamental aspect of a virus and propose to use this feature, instead of the capsid, to define viruses. Although the eclipse phase is informative in terms of virus description and could be added to our virus definition, we think that such a feature cannot be solely used to define viruses, because it is a phenotypic trait that cannot readily be assigned to a particular gene or set of genes (unlike the capsid) in the viral genome. Consequently, a definition of viruses that is based only on such properties would have a pre-Darwinian flavour (similar to the prokaryote or eukaryote classification system).

Phenotypic classification systems can easily be rendered obsolete by further discovery or lead to endless discussions about the definition of the phenotypic properties themselves. For example, the prokaryote and eukaryote classification system has been challenged by the discovery of bacteria (prokaryotes) that have a nucleus3. If viruses are defined as organisms with a cycle of disappearance and reappearance, it could be argued that most eukaryotes also have this feature. Indeed, if the human organism is assimilated as a functional integrated collection of organs, one might also consider that the organism has disappeared in the germinal cells and that the human cycle alternates between various forms, one that is a collection of organs and one that is a single-celled organism during reproduction. Similarly, the virus alternates between a cellular form of organization (the intracellular viral factory), a simple molecular form (the viral genome) and a complex molecular form (the virion). Remarkably, a cellular organism can be also reconstituted (at least in the laboratory) from a single molecule. A recent study showed that injection of an in vitro synthesized bacterial genome into a recipient cell led to the generation of bacteria with phenotypes that corresponded to the inoculated genome4. This experimental work clearly demonstrated that an isolated bacterial genome is sufficient to create a cellular organism. If this can be achieved in the laboratory, we cannot exclude the possibility that it could happen in nature. Therefore, in these experiments, bacterial and viral nucleic acids5 are strictly comparable, making it necessary to classify them based on their coding capacity.

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References

  1. Raoult, D. & Forterre, P. Redefining viruses: lessons from Mimivirus. Nature Rev. Microbiol. 6, 315–319 (2008).

    Article  CAS  Google Scholar 

  2. Wolkowicz, R. & Schaechter, M. What makes a virus a virus? Nature Rev. Microbiol. 16 July 2008 (doi: 10.1038/nrmicro1858-c1).

    Article  CAS  PubMed  Google Scholar 

  3. Fuerst, J. A. Intracellular compartmentation in planctomycetes. Annu. Rev. Microbiol. 59, 299–328 (2005).

    Article  CAS  PubMed  Google Scholar 

  4. Lartigue, C. et al. Genome transplantation in bacteria: changing one species to another. Science 317, 632–638 (2007).

    Article  CAS  PubMed  Google Scholar 

  5. Smith, H. O., Hutchison, C. A., Pfannkoch, C. & Venter, J. C. Generating a synthetic genome by whole genome assembly: phiX174 bacteriophage from synthetic oligonucleotides. Proc. Natl Acad. Sci. USA 100, 15440–15445 (2003).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  6. Bamford, D. H., Grimes, J. M. & Stuart, D. I. What does structure tell us about virus evolution? Curr. Opin. Struct. Biol. 15, 655–663 (2005).

    Article  CAS  PubMed  Google Scholar 

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Authors and Affiliations

  1. Didier Raoult is at the Unité des Rickettsies, IRD-CNRS UMR 6236, IFR-48, Faculté de Médecine, 27 Bd Jean Moulin, 13385 Marseille, France.,

    Didier Raoult

  2. Patrick Forterre is at the Institut Pasteur, 25 rue du Docteur Roux, 75015 Paris1, France, and the University Paris Sud, Institut de Génétique et Microbiologie, CNRS, UMR 8626 IRF-115, Centre d'Orsay, 91405 Orsay, France.,

    Patrick Forterre

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  1. Didier Raoult
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Correspondence to Didier Raoult.

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Raoult, D., Forterre, P. What makes a virus a virus: reply from Raoult and Forterre. Nat Rev Microbiol 6, 643 (2008). https://doi.org/10.1038/nrmicro1858-c2

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