Abstract

Viruses are the most abundant living entities and probably had a major role in the evolution of life, but are still defined using negative criteria. Here, we propose to divide biological entities into two groups of organisms: ribosome-encoding organisms, which include eukaryotic, archaeal and bacterial organisms, and capsid-encoding organisms, which include viruses. Other replicons (for example, plasmids and viroids) can be termed 'orphan replicons'. Based on this suggested classification system, we propose a new definition for a virus — a capsid-encoding organism that is composed of proteins and nucleic acids, self-assembles in a nucleocapsid and uses a ribosome-encoding organism for the completion of its life cycle.

Author 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.
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.

Correspondence to: Didier Raoult¹ Email: didier.raoult@gmail.com