title: Ancient invasion of an extinct gammaretrovirus in cetaceans.
abstract: Endogenous gammaretroviruses (EGVs) have been widely studied in terrestrial mammals but seldom so in marine species. A genomic mining of the bottlenose dolphin (Tursiops truncatus) genome revealed a new EGV, termed Tursiops truncatus endogenous retrovirus (TTEV), which is divergent from extant mammalian EGVs. Molecular clock dating estimated the invasion time of TTEV into the host genome to be approximately 10-19 million years ago (MYA), while a previously identified killer whale endogenous gammaretrovirus (KWERV) was estimated to have invaded the host genome approximately 3-5 MYA. Using a PCR-based technique, we then verified that similar endogenous viruses exist in nine cetacean genomes. Phylogenetic analysis revealed that these cetacean EGVs are highly divergent from their counterparts in other mammals, including KWERV from the killer whale. In sum, we conclude that there have been at least two invasion episodes of EGVs into cetaceans during their evolutionary history.
authors.affiliation: Institute of Molecular Ecology and Evolution, Institutes for Advanced Interdisciplinary Research, East China Normal University, Shanghai 200062, China.
authors.forename: Lina
authors.initials: L
authors.lastname: Wang
authors.forename: Qiuyuan
authors.initials: Q
authors.lastname: Yin
authors.forename: Guimei
authors.initials: G
authors.lastname: He
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Rossiter
authors.forename: Edward C
authors.initials: EC
authors.lastname: Holmes
authors.forename: Jie
authors.initials: J
authors.lastname: Cui
mesh_terms: D000818:Animals; D002591:Cetacea / Q000235:genetics / Q000821:virology*; D016000:Cluster Analysis; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D017988:Gammaretrovirus / Q000235:genetics / Q000302:isolation & purification*; D016679:Genome, Viral; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid
chemical_list: D004279:DNA, Viral