Download Giant viruses are old and ubiquitous Hiroyuki Ogata, Adam Monier

Giant viruses are old and ubiquitous
Hiroyuki Ogata, Adam Monier, Jean-Michel Claverie
CNRS IGS UPR2589, Marseille
Evolutionary analysis of viruses has long been considered unfeasible (or at least often
avoided) for two main reasons: their reputed propensity to randomly acquire genetic material
from their host and their reputed very high sequence divergence rate. The generality of this
vision now deserves to be revisited for DNA viruses in light of the increasing amount of
available genomic sequence data. I will first talk about very old origins of DNA viruses along
with evidences from our mimivirus genome analyses. Then, I will present a couple of our
recent bioinformatics studies. Our results show that giant virus genomes are under strong
functional constraints comparable to those on our own genome. Our results argue against
frequent genetic transfers, if any, to large DNA viruses from their hosts. Our results suggest
that giant viruses (“Mimiviridae”) represent one of the main and diverse components of the marine
eukaryotic viruses. Finally, I will talk about an essential dichotomy of the viral gene pool, one part
shared with cellular and distantly related viral genomes and the other having been confined for a long
period of time in small groups of viruses.
1. Raoult D, Audic S, Robert C, Abergel C, Renesto P, Ogata H, La Scola B, Suzan M, Claverie JM. The 1.2megabase genome sequence of Mimivirus. Science. 2004, 306:1344-50.
2. Ogata H., Abergel C., Raoult D., Claverie J.-M. Response to comment on “the 1.2-megabase genome
sequence of Mimivirus”. Science, 2005, 308, 1114b.
3. Claverie JM, Ogata H, Audic S, Abergel C, Suhre K, Fournier PE. Mimivirus and the emerging concept of
"giant" virus. Virus Res. 2006, 117:133-44.
4. Ogata H, Claverie JM. Unique genes in giant viruses: regular substitution pattern and anomalously short size.
Genome Res. 2007, 17:1353-61.
5. Monier A, Claverie JM, Ogata H. Horizontal gene transfer and nucleotide compositional anomaly in large
DNA viruses. BMC Genomics. 2007, 8:456.
6. Monier A, Larsen JB, Sandaa RA, Bratbak G, Claverie JM, Ogata H. Marine mimivirus relatives are
probably large algal viruses. Virol J. 2008, 5:12