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

Abstract

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.

Transposable elements as genetic accelerators of evolution: contribution to genome size, gene regulatory network rewiring and morphological innovation

“…As these proteins can mediate intercellular transfer of Arc mRNA, it is possible that Arc is involved in the intercellular communication of genetic information via mRNA transfer between neurons in the brain (Pastuzyn et al, 2018). In addition, in other animals, LTR-retrotransposon sequences can play a variety of important biological roles (for details, see Horie, 2019).…”

Endogenous Viral Elements in Shrew Genomes Provide Insights into Pestivirus Ancient History

“…Non-retroviral RNA virus-derived EVEs arise from a conjunction of relatively rare events: (i) production of DNA genomic material, using retrotransposon encoded reverse transcriptase ( Horie et al . 2010 ; Horie 2019 ); (ii) integration in the host chromosome of germ line cells; and (iii) overcoming genetic drift and/or natural selection at the population until fixation ( Holmes 2011 ; Aiewsakun and Katzourakis 2015 ). EVEs thus reflect long-term and intimate interactions of viruses with their hosts, and their identification can reveal insights into past and present host distributions of viral genera and families.…”

Discovery of Flaviviridae-derived endogenous viral elements in shrew genomes provide novel insights into Pestivirus ancient history

“…These non-retroviruses can derive from dsDNA (Aswad and Katzourakis, 2014; Li and Li, 2015; Liu et al, 2020), ssDNA (Belyi et al, 2010a; Katzourakis and Gifford, 2010a; Kobayashi et al, 2019), dsRNA (Horie et al, 2010; Katzourakis and Gifford, 2010b; Liu et al, 2012), and even ssRNA viruses (Crochu et al, 2004; Flynn and Moreau, 2019; Horie et al, 2010; Lequime and Lambrechts, 2017). Non-retroviral RNA virus-derived EVEs arise from a conjunction of relatively rare events: i) production of DNA genomic material, using retrotransposon encoded reverse transcriptase (Horie, 2019; Horie et al, 2010), ii) integration in the host chromosome of germ-line cells, and iii) overcoming genetic drift and/or natural selection at the population until fixation (Aiewsakun and Katzourakis, 2015a; Holmes, 2011). EVEs thus reflect long-term and intimate interactions of viruses with their hosts, and their identification can reveal insights into past and present host distributions of viral genera and families.…”