Tsangaras Kyriakos, Mayer Jens, Alquezar-Planas David E, Greenwood Alex D
Department of Translational Genetics, The Cyprus Institute of Neurology and Genetics, 6 International Airport Ave., 2370 Nicosia, Cyprus.
Department of Human Genetics, Center of Human and Molecular Biology, Medical Faculty, University of Saarland, 66421 Homburg, Germany.
Viruses. 2015 Nov 24;7(11):6089-107. doi: 10.3390/v7112927.
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.
对北极熊（Ursus maritimus）组织的转录组分析鉴定出了与猪内源性逆转录病毒（PERV）相似的序列。基于这些序列，从北极熊基因组草图序列中鉴定出一种新描述的内源性逆转录病毒的四个前病毒拷贝和15个单独的长末端重复序列（LTR）。通过对棕熊（Ursus arctos）和黑熊（Ursus americanus）进行PCR分析，鉴定出了密切相关的序列，但在非熊科熊类物种中未发现。因此，该病毒被命名为UrsusERV。观察到两组不同的LTR，包括一种重组ERV，其包含属于每组的一个LTR，这表明最近至少发生了两次UrsusERV变体的基因组入侵。基于前病毒LTR差异和熊科动物整合位点保守性的年龄估计表明，该病毒群体只有几百万年的历史。最年轻的前病毒是北极熊特有的，具有完整的开放阅读框（ORF），可能编码功能蛋白。对UrsusERV共有蛋白序列的系统发育分析表明，它是猪、长臂猿和考拉逆转录病毒进化枝的一部分。该病毒的年轻年龄估计和谱系特异性表明，UrsusERV是最近从未知宿主跨物种传播而来的，并且该病毒群体是在哺乳动物中鉴定出的最年轻的ERV之一。
