Dissemination of Internal Ribosomal Entry Sites (IRES) Between Viruses by Horizontal Gene Transfer

• Published in: Viruses Vol. 12; no. 6; p. 612
• Main Authors: Arhab, Yani, Bulakhov, Alexander G, Pestova, Tatyana V, Hellen, Christopher U T
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI 04-06-2020; MDPI AG
• Subjects: 5' Untranslated Regions; Animals; Flavivirus; Gene Expression Regulation, Viral; Gene Transfer, Horizontal; Hepacivirus; Horizontal gene transfer; Humans; Internal Ribosome Entry Sites; IRES; Pegivirus; Pestivirus; Protein Biosynthesis; Review; RNA, Viral - genetics; RNA, Viral - metabolism; Virus Diseases - virology; Viruses - genetics; Viruses - growth & development; Viruses - metabolism; Pestivirus; Picornavirus; Recombination; Translation; IRES; Flavivirus; Hepacivirus; Pegivirus; Horizontal gene transfer
• ISSN: 1999-4915; 1999-4915
• DOI: 10.3390/v12060612

Members of
and of the
,
and
genera of
all contain an internal ribosomal entry site (IRES) in the 5'-untranslated region (5'UTR) of their genomes. Each class of IRES has a conserved structure and promotes 5'-end-independent initiation of translation by a different mechanism. Picornavirus 5'UTRs, including the IRES, evolve independently of other parts of the genome and can move between genomes, most commonly by intratypic recombination. We review accumulating evidence that IRESs are genetic entities that can also move between members of different genera and even between families. Type IV IRESs, first identified in the
genus, have subsequently been identified in over 25 genera of
, juxtaposed against diverse coding sequences. In several genera, members have either type IV IRES or an IRES of type I, II or III. Similarly, in the genus
, members contain either a type IV IRES or an unrelated type; both classes of IRES also occur in members of the genus
. IRESs utilize different mechanisms, have different factor requirements and contain determinants of viral growth, pathogenesis and cell type specificity. Their dissemination between viruses by horizontal gene transfer has unexpectedly emerged as an important facet of viral evolution.