title: Complete genome analysis of a frog virus 3 (FV3) isolate and sequence comparison with isolates of differing levels of virulence.
abstract: BACKGROUND
  Frog virus 3 (FV3) is the type species of the genus Ranavirus, and in the past few decades, FV3 infections have resulted in considerable morbidity and mortality in a range of wild and cultivated amphibian species in the Americas, Europe, and Asia. The reasons for the pathogenicity of FV3 are not well understood.
  
  
  RESULTS
  We investigated three FV3 isolates designated SSME, wt-FV3, and aza-Cr, and reported that our wt-FV3 and aza-Cr strains showed similar levels of virulence, while SSME was the least virulent in an in vivo study with Lithiobates pipiens tadpoles. Using 454 GS-FLX sequencing technology, we sequenced SSME and compared it to the published wt-FV3 genome. SSME had multiple amino acid deletions in ORFs 49/50L, 65L, 66L, and 87L, which may explain its reduced virulence. We also investigated repeat regions and found that repeat copy number differed between isolates, with only one group of 3 isolates and 1 pair of isolates being identical at all 3 locations.
  
  
  CONCLUSIONS
  In this study we have shown that genetic variability is present between closely related FV3 isolates, both in terms of deletions/insertions, and even more so at select repeat locations. These genomic areas with deletions/insertions may represent regions that affect virulence, and therefore require investigation. Furthermore, we have identified repeat regions that may prove useful in future phylogeographical tracking and identification of ranaviral strains across different environmental regions.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Morrison
authors.forename: Shawn
authors.initials: S
authors.lastname: Garner
authors.forename: Pierre
authors.initials: P
authors.lastname: Echaubard
authors.forename: David
authors.initials: D
authors.lastname: Lesbarrères
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Kyle
authors.affiliation: Department of Biology, Trent University, 1600 East Bank Dr,, Peterborough, Ontario K9J 7B8, Canada. craigbrunetti@trentu.ca.
authors.forename: Craig R
authors.initials: CR
authors.lastname: Brunetti
mesh_terms: D000818:Animals; D004266:DNA Virus Infections / Q000473:pathology / Q000662:veterinary; D004279:DNA, Viral / Q000737:chemistry* / Q000235:genetics*; D014644:Genetic Variation; D016679:Genome, Viral; D007814:Larva / Q000821:virology; D008969:Molecular Sequence Data; D011894:Rana pipiens / Q000821:virology; D017995:Ranavirus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity*; D017422:Sequence Analysis, DNA; D017384:Sequence Deletion; D014481:United States; D014764:Viral Proteins / Q000235:genetics; D014774:Virulence
chemical_list: D004279:DNA, Viral; D014764:Viral Proteins