Interactions among eukaryotes, retrotransposons and riboviruses: endogenous riboviral elements in eukaryotic genomes

• Published in: Genes & Genetic Systems Vol. 94; no. 6; pp. 253 - 267
• Main Author: Horie, Masayuki
• Format: Journal Article
• Language: English
• Published: Japan The Genetics Society of Japan 01.12.2019; Japan Science and Technology Agency
• Subjects: Deoxyribonucleic acid; DNA; DNA biosynthesis; endogenous viral element; evolution; Genomes; Intermediates; Nucleotide sequence; retrotransposon; Reverse transcription; Ribonucleic acid; RNA; RNA viruses; RNA-directed DNA polymerase; retrotransposon; endogenous viral element; evolution
• ISSN: 1341-7568; 1880-5779; 1880-5779
• DOI: 10.1266/ggs.18-00049

Riboviruses are viruses that have RNA genomes and replicate only via RNA intermediates. Although they do not require a DNA phase for replication and do not encode reverse transcriptase, the presence of DNA forms of riboviral sequences in ribovirus-infected cells has been reported since the 1970s. Additionally, heritable ribovirus-derived sequences, called riboviral endogenous viral elements (EVEs), have been found in the genomes of many eukaryotes. These are now thought to be formed by the reverse transcription machineries of retrotransposons within eukaryotic genomes sometimes referred to as selfish elements. Surprisingly, some reverse-transcribed riboviral DNAs (including EVEs) provide physiological functions for their hosts, suggesting the occurrence of novel interactions among eukaryotic genomes, retrotransposons and riboviruses, and opening the door to new avenues of investigation. Here I review current knowledge on these triangular interactions, and discuss future directions in this field.