title: Comparative paleovirological analysis of crustaceans identifies multiple widespread viral groups.
abstract: BACKGROUND
  The discovery of many fragments of viral genomes integrated in the genome of their eukaryotic host (endogenous viral elements; EVEs) has recently opened new avenues to further our understanding of viral evolution and of host-virus interactions. Here, we report the results of a comprehensive screen for EVEs in crustaceans. Following up on the recent discovery of EVEs in the terrestrial isopod, Armadillidium vulgare, we scanned the genomes of six crustacean species: a terrestrial isopod (Armadillidium nasatum), two water fleas (Daphnia pulex and D. pulicaria), two copepods (the salmon louse, Lepeophtheirus salmonis and Eurytemora affinis), and a freshwater amphipod (Hyalella azteca).
  
  
  RESULTS
  In total, we found 210 EVEs representing 14 different lineages belonging to five different viral groups that are present in two to five species: Bunyaviridae (-ssRNA), Circoviridae (ssDNA), Mononegavirales (-ssRNA), Parvoviridae (ssDNA) and Totiviridae (dsRNA). The identification of shared orthologous insertions between A. nasatum and A. vulgare indicates that EVEs have been maintained over several millions of years, although we did not find any evidence supporting exaptation. Overall, the different degrees of EVE degradation (from none to >10 nonsense mutations) suggest that endogenization has been recurrent during the evolution of the various crustacean taxa. Our study is the first to report EVEs in D. pulicaria, E. affinis and H. azteca, many of which are likely to result from recent endogenization of currently circulating viruses.
  
  
  CONCLUSIONS
  In conclusion, we have unearthed a large diversity of EVEs from crustacean genomes, and shown that four of the five viral groups we uncovered (Bunyaviridae, Circoviridae, Mononegavirales, Parvoviridae) were and may still be present in three to four highly divergent crustacean taxa. In addition, the discovery of recent EVEs offers an interesting opportunity to characterize new exogenous viruses currently circulating in economically or ecologically important copepod species.
authors.affiliation: Université de Poitiers, UMR CNRS 7267 Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, building B8-B35, 6 rue Michel Brunet, TSA 51106 F-86073 Poitiers, Cedex 9 France.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Metegnier
authors.affiliation: Université de Poitiers, UMR CNRS 7267 Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, building B8-B35, 6 rue Michel Brunet, TSA 51106 F-86073 Poitiers, Cedex 9 France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Becking
authors.affiliation: Université de Poitiers, UMR CNRS 7267 Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, building B8-B35, 6 rue Michel Brunet, TSA 51106 F-86073 Poitiers, Cedex 9 France.
authors.forename: Mohamed Amine
authors.initials: MA
authors.lastname: Chebbi
authors.affiliation: Université de Poitiers, UMR CNRS 7267 Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, building B8-B35, 6 rue Michel Brunet, TSA 51106 F-86073 Poitiers, Cedex 9 France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Giraud
authors.affiliation: Université de Poitiers, UMR CNRS 7267 Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, building B8-B35, 6 rue Michel Brunet, TSA 51106 F-86073 Poitiers, Cedex 9 France.
authors.forename: Bouziane
authors.initials: B
authors.lastname: Moumen
authors.affiliation: Department of Biology, Reed College, Portland, OR USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Schaack
authors.affiliation: Université de Poitiers, UMR CNRS 7267 Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, building B8-B35, 6 rue Michel Brunet, TSA 51106 F-86073 Poitiers, Cedex 9 France.
authors.forename: Richard
authors.initials: R
authors.lastname: Cordaux
authors.affiliation: Université de Poitiers, UMR CNRS 7267 Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, building B8-B35, 6 rue Michel Brunet, TSA 51106 F-86073 Poitiers, Cedex 9 France.
authors.forename: Clément
authors.initials: C
authors.lastname: Gilbert
keywords: Bunyaviridae; Circoviridae; Copepoda; Crustacea; Endogenous viral elements; Mononegavirales; Paleovirology; Parvoviridae; Totiviridae; Virus