title: Diversity of Viruses Infecting the Green Microalga Ostreococcus lucimarinus.
abstract: The functional diversity of eukaryotic viruses infecting a single host strain from seawater samples originating from distant marine locations is unknown. To estimate this diversity, we used lysis plaque assays to detect viruses that infect the widespread species Ostreococcus lucimarinus, which is found in coastal and mesotrophic systems, and O. tauri, which was isolated from coastal and lagoon sites from the northwest Mediterranean Sea. Detection of viral lytic activities against O. tauri was not observed using seawater from most sites, except those close to the area where the host strain was isolated. In contrast, the more cosmopolitan O. lucimarinus species recovered viruses from locations in the Atlantic and Pacific Oceans and the Mediterranean Sea. Six new O. lucimarinus viruses (OlVs) then were characterized and their genomes sequenced. Two subgroups of OlVs were distinguished based on their genetic distances and on the inversion of a central 32-kb-long DNA fragment, but overall their genomes displayed a high level of synteny. The two groups did not correspond to proximity of isolation sites, and the phylogenetic distance between these subgroups was higher than the distances observed among viruses infecting O. tauri. Our study demonstrates that viruses originating from very distant sites are able to infect the same algal host strain and can be more diverse than those infecting different species of the same genus. Finally, distinctive features and evolutionary distances between these different viral subgroups does not appear to be linked to biogeography of the viral isolates.
  
  
  OBJECTIVE
  Marine eukaryotic phytoplankton virus diversity has yet to be addressed, and more specifically, it is unclear whether diversity is connected to geographical distance and whether differential infection and lysis patterns exist among such viruses that infect the same host strain. Here, we assessed the genetic distance of geographically segregated viruses that infect the ubiquitous green microalga Ostreococcus. This study provides the first glimpse into the diversity of predicted gene functions in Ostreococcus viruses originating from distant sites and provides new insights into potential host distributions and restrictions in the world oceans.
authors: CNRS UMR 7232, Sorbonne Universités, Observatoire Océanologique de Banyuls (OOB), Banyuls sur mer, France.
authors: Evelyne
authors: E
authors: Derelle
authors: University of Exeter, Biosciences, Exeter, United Kingdom Monterey Bay Aquarium Research Institute (MBARI), Moss Landing, California, USA.
authors: Adam
authors: A
authors: Monier
authors: Laboratoire Génome et Développement des Plantes, UMR 5096 CNRS, Université de Perpignan Via Domitia, Perpignan, France.
authors: Richard
authors: R
authors: Cooke
authors: Monterey Bay Aquarium Research Institute (MBARI), Moss Landing, California, USA Integrated Microbial Biodiversity Program, Canadian Institute for Advanced Research, Toronto, Canada.
authors: Alexandra Z
authors: AZ
authors: Worden
authors: CNRS UMR 7232, Sorbonne Universités, Observatoire Océanologique de Banyuls (OOB), Banyuls sur mer, France nigel.grimsley@obs-banyuls.fr h.moreau@obs-banyuls.fr.
authors: Nigel H
authors: NH
authors: Grimsley
authors: CNRS UMR 7232, Sorbonne Universités, Observatoire Océanologique de Banyuls (OOB), Banyuls sur mer, France nigel.grimsley@obs-banyuls.fr h.moreau@obs-banyuls.fr.
authors: Hervé
authors: H
authors: Moreau
mesh_terms: D001267:Atlantic Ocean; D044822:Biodiversity; D000460:Chlorophyta / Q000821:virology*; D016000:Cluster Analysis; D023061:Gene Order; D016679:Genome, Viral; D008522:Mediterranean Sea; D008969:Molecular Sequence Data; D010140:Pacific Ocean; D010802:Phylogeny; D012623:Seawater / Q000382:microbiology / Q000821:virology; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D026801:Synteny; D010948:Viral Plaque Assay; D014780:Viruses / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*