Remarkable diversity of endogenous viruses in a crustacean genome.
Bottom Line: These fragments result from endogenization, that is, integration of the viral genome into the host germline genome followed by vertical inheritance.We show that viral endogenization occurred recurrently during the evolution of isopods and that A. vulgare viral lineages were involved in multiple host switches that took place between widely divergent taxa.More generally, our results underline the power of paleovirology in characterizing the viral diversity currently infecting eukaryotic taxa.
Affiliation: Université de Poitiers, UMR CNRS 7267 Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, Poitiers, France.Show MeSH
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Mentions: To identify EVEs in whole-genome sequences of the isopod crustacean A. vulgare, we first performed a TBLASTX search using all complete viral genomes publicly available in GenBank and EMBL (January 2014) as queries (n = 2,048). We then used all hits resulting from this search (n = 10,727) as queries to carry out a reciprocal BLASTX on the nonredundant protein database of the NCBI. This approach yielded a total of 54 A. vulgare genome sequences of unambiguous viral origin, ranging from 42 to 588 aa in length (average = 173 aa) and showing 46–78% aa similarity (average = 58%) to their most closely related exogenous viral protein sequences (fig. 1 and supplementary table S1, Supplementary Material online). The 54 EVEs were assigned to four different families (Bunyaviridae, Circoviridae, Parvoviridae, and Totiviridae) and one order (Mononegavirales), representing three of the seven types of viral genomes (-ssRNA, dsRNA, and ssDNA). Among those families/order, the Circoviridae and Totiviridae families are not currently reported by the ICTV (King et al. 2011) to infect arthropods (but see e.g., Wu et al. 2010; Rosario et al. 2012). The diversity of EVEs discovered in the A. vulgare genome is remarkable in that most previously published paleovirology studies have reported less than 20 EVEs and/or less than 4 different viral families in a given genome (Feschotte and Gilbert 2012).Fig. 1.—
Affiliation: Université de Poitiers, UMR CNRS 7267 Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, Poitiers, France.