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Open Access Highly Accessed Research

Taxonomic distribution of large DNA viruses in the sea

Adam Monier, Jean-Michel Claverie and Hiroyuki Ogata*

Author Affiliations

Structural and Genomic Information Laboratory, CNRS-UPR 2589, IFR-88, Université de la Méditerranée Parc Scientifique de Luminy, avenue de Luminy, FR-13288 Marseille, France

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Genome Biology 2008, 9:R106  doi:10.1186/gb-2008-9-7-r106

Published: 3 July 2008

Abstract

Background

Viruses are ubiquitous and the most abundant biological entities in marine environments. Metagenomics studies are increasingly revealing the huge genetic diversity of marine viruses. In this study, we used a new approach - 'phylogenetic mapping' - to obtain a comprehensive picture of the taxonomic distribution of large DNA viruses represented in the Sorcerer II Global Ocean Sampling Expedition metagenomic data set.

Results

Using DNA polymerase genes as a taxonomic marker, we identified 811 homologous sequences of likely viral origin. As expected, most of these sequences corresponded to phages. Interestingly, the second largest viral group corresponded to that containing mimivirus and three related algal viruses. We also identified several DNA polymerase homologs closely related to Asfarviridae, a viral family poorly represented among isolated viruses and, until now, limited to terrestrial animal hosts. Finally, our approach allowed the identification of a new combination of genes in 'viral-like' sequences.

Conclusion

Albeit only recently discovered, giant viruses of the Mimiviridae family appear to constitute a diverse, quantitatively important and ubiquitous component of the population of large eukaryotic DNA viruses in the sea.