Article An Evolutionarily Young Polar Bear (Ursus maritimus) Endogenous Retrovirus Identified from Next Generation Sequence Data Kyriakos Tsangaras 1,*, Jens Mayer 2, David E. Alquezar-Planas 3 and Alex D. Greenwood 3,4,* Received: 7 September 2015; Accepted: 11 November 2015; Published: 24 November 2015 Academic Editors: Johnson Mak, Peter Walker and Marcus Thomas Gilbert 1 Department of Translational Genetics, The Cyprus Institute of Neurology and Genetics, 6 International Airport Ave., 2370 Nicosia, Cyprus 2 Department of Human Genetics, Center of Human and Molecular Biology, Medical Faculty, University of Saarland, 66421 Homburg, Germany;
[email protected] 3 Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research Berlin, Alfred-Kowalke-Str. 17, 10315 Berlin, Germany;
[email protected] 4 Department of Veterinary Medicine, Freie Universität Berlin, Oertzenweg 19b, 14163 Berlin, Germany * Correspondence:
[email protected] (K.T.);
[email protected] (A.D.G.); Tel.: +357-22-392-783 (K.T.); +49-30-5168-255 (A.D.G.) 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.