title: An Intact Retroviral Gene Conserved in Spiny-Rayed Fishes for over 100 My.
abstract: We have identified a retroviral envelope gene with a complete, intact open reading frame (ORF) in 20 species of spiny-rayed fishes (Acanthomorpha). The taxonomic distribution of the gene, "percomORF", indicates insertion into the ancestral lineage >110 Ma, making it the oldest known conserved gene of viral origin in a vertebrate genome. Underscoring its ancient provenence, percomORF exists as an isolated ORF within the intron of a widely conserved host gene, with no discernible proviral sequence nearby. Despite its remarkable age, percomORF retains canonical features of a retroviral glycoprotein, and tests for selection strongly suggest cooption for a host function. Retroviral envelope genes have been coopted for a role in placentogenesis by numerous lineages of mammals, including eutherians and marsupials, representing a variety of placental structures. Therefore percomORF's presence within the group Percomorpha-unique among spiny-finned fishes in having evolved placentation and live birth-is especially intriguing.
authors.affiliation: Biology Department, Boston College, Chestnut Hill, MA.
authors.forename: Jamie E
authors.initials: JE
authors.lastname: Henzy
authors.affiliation: MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Gifford
authors.affiliation: Biology Department, Boston College, Chestnut Hill, MA.
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Kenaley
authors.affiliation: Biology Department, Boston College, Chestnut Hill, MA.
authors.forename: Welkin E
authors.initials: WE
authors.lastname: Johnson
mesh_terms: D000818:Animals; D005075:Biological Evolution; D017124:Conserved Sequence; D020077:Endogenous Retroviruses / Q000235:genetics*; D019143:Evolution, Molecular; D005399:Fishes / Q000235:genetics* / Q000821:virology*; D015686:Gene Products, env / Q000235:genetics*; D016366:Open Reading Frames; D010802:Phylogeny; D011533:Proviruses / Q000235:genetics; D012191:Retroviridae Proteins / Q000235:genetics; D017422:Sequence Analysis, DNA / Q000379:methods; D014759:Viral Envelope Proteins / Q000235:genetics
chemical_list: D015686:Gene Products, env; D012191:Retroviridae Proteins; D014759:Viral Envelope Proteins
keywords: endogenous retrovirus; evolution.; viral gene cooption