Mimivirus and the emerging concept of "giant" virus.
The recently discovered Acanthamoeba polyphaga Mimivirus is the largest known DNA virus. Its particle size (750 nm), genome length (1.2 million bp) and large gene repertoire (911 protein coding genes) blur the established boundaries between viruses and parasitic cellular organisms. In addition, the analysis of its genome sequence identified many types of genes never before encountered in a virus, including aminoacyl-tRNA synthetases and other central components of the translation machinery previously thought to be the signature of cellular organisms. In this article, we examine how the finding of such a giant virus might durably influence the way we look at microbial biodiversity, and lead us to revise the classification of microbial domains and life forms. We propose to introduce the word "girus" to recognize the intermediate status of these giant DNA viruses, the genome complexity of which makes them closer to small parasitic prokaryotes than to regular viruses.
Information Génomique et Structurale, CNRS UPR 2589, IBSM, Parc Scientifique de Luminy, 163 Avenue de Luminy, Case 934, 13288 Marseille Cedex 9, France. Jean-Michel.Claverie@igs.cnrs-mrs.fr
Jean-Michel
JM
Claverie
Hiroyuki
H
Ogata
Stéphane
S
Audic
Chantal
C
Abergel
Karsten
K
Suhre
Pierre-Edouard
PE
Fournier
D000048:Acanthamoeba / Q000821:virology*; D000595:Amino Acid Sequence; D000818:Animals; D004267:DNA Viruses / Q000235:genetics*; D019143:Evolution, Molecular; D016679:Genome, Viral; D008969:Molecular Sequence Data; D014764:Viral Proteins / Q000737:chemistry
D014764:Viral Proteins