title: An Evolutionarily Young Polar Bear (Ursus maritimus) Endogenous Retrovirus Identified from Next Generation Sequence Data.
abstract: Transcriptome analysis of polar bear (Ursus maritimus) tissues identified sequences with similarity to Porcine Endogenous Retroviruses (PERV). Based on these sequences, four proviral copies and 15 solo long terminal repeats (LTRs) of a newly described endogenous retrovirus were characterized from the polar bear draft genome sequence. Closely related sequences were identified by PCR analysis of brown bear (Ursus arctos) and black bear (Ursus americanus) but were absent in non-Ursinae bear species. The virus was therefore designated UrsusERV. Two distinct groups of LTRs were observed including a recombinant ERV that contained one LTR belonging to each group indicating that genomic invasions by at least two UrsusERV variants have recently occurred. Age estimates based on proviral LTR divergence and conservation of integration sites among ursids suggest the viral group is only a few million years old. The youngest provirus was polar bear specific, had intact open reading frames (ORFs) and could potentially encode functional proteins. Phylogenetic analyses of UrsusERV consensus protein sequences suggest that it is part of a pig, gibbon and koala retrovirus clade. The young age estimates and lineage specificity of the virus suggests UrsusERV is a recent cross species transmission from an unknown reservoir and places the viral group among the youngest of ERVs identified in mammals.
authors.affiliation: Department of Translational Genetics, The Cyprus Institute of Neurology and Genetics, 6 International Airport Ave., 2370 Nicosia, Cyprus. ktsangaras@gmail.com.
authors.forename: Kyriakos
authors.initials: K
authors.lastname: Tsangaras
authors.affiliation: Department of Human Genetics, Center of Human and Molecular Biology, Medical Faculty, University of Saarland, 66421 Homburg, Germany. jens.mayer@uniklinikum-saarland.de.
authors.forename: Jens
authors.initials: J
authors.lastname: Mayer
authors.affiliation: Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research Berlin, Alfred-Kowalke-Str. 17, 10315 Berlin, Germany. alquezar@izw-berlin.de.
authors.forename: David E
authors.initials: DE
authors.lastname: Alquezar-Planas
authors.affiliation: Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research Berlin, Alfred-Kowalke-Str. 17, 10315 Berlin, Germany. greenwood@izw-berlin.de.|Department of Veterinary Medicine, Freie Universität Berlin, Oertzenweg 19b, 14163 Berlin, Germany. greenwood@izw-berlin.de.
authors.forename: Alex D
authors.initials: AD
authors.lastname: Greenwood
mesh_terms: D000818:Animals; D020077:Endogenous Retroviruses / Q000235:genetics* / Q000302:isolation & purification*; D005260:Female; D059014:High-Throughput Nucleotide Sequencing; D008297:Male; D016366:Open Reading Frames; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011533:Proviruses / Q000235:genetics / Q000302:isolation & purification; D017385:Sequence Homology; D020079:Terminal Repeat Sequences; D001503:Ursidae / Q000235:genetics* / Q000821:virology*
keywords: Ursidinae; Ursus; endogenous retrovirus; genomics; next generation sequencing; phylogenetics; polar bear; retrovirus