title: Redefining viruses: lessons from Mimivirus.
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.
authors.affiliation: Unité des Rickettsies, IRD-CNRS UMR 6236, IFR-48, Faculté de Médecine, 27 Bd Jean Moulin, 13385 Marseille, France. didier.raoult@gmail.com
authors.forename: Didier
authors.initials: D
authors.lastname: Raoult
authors.forename: Patrick
authors.initials: P
authors.lastname: Forterre
mesh_terms: D002213:Capsid / Q000737:chemistry; D036022:Capsid Proteins / Q000737:chemistry*; D004267:DNA Viruses / Q000235:genetics* / Q000502:physiology; D019143:Evolution, Molecular; D016679:Genome, Viral; D012093:Replicon
chemical_list: D036022:Capsid Proteins