Kutschera LS, Wolfinger MT.
Evolutionary traits of tick-borne encephalitis virus: pervasive non-coding RNA structure conservation and molecular epidemiology
Virus Evol. 2022;8(1):veac051. doi:10.1093/ve/veac051
TBE virus is an enveloped, single-stranded, (+)-sense flavivirus that contains a non-segmented, 5`-capped non-polyadenylated RNA. The genome encodes a single open reading frame that is flanked by highly structured untranslated regions (UTRs) of variable length. These UTRs are involved in various regulating processes including viral replication, genome packaging and immune response. In addition to the 5`-UTRs, the genome of TBE virus also contains a 3`-UTR which has various functions among which is the ability to dysregulate the host mRNA turnover by stalling endogenous exoribonucleases at structurally well-defined RNAs in the viral 3`-UTR.
The so far classified seven subtypes of TBE virus differ in their phylogeography, virulence and pathogenicity. The 3`-UTR is involved in mediating immune escape and pathogenicity. In a recent study, the genetic diversity and phylogeographic spread of a set of 220 known viral genomes has been investigated and it was shown that the 3`-UTRs are associated with neurotropism. TBE virus shows a large degree of 3`-UTR variability within particular subtypes and lineages with pervasive conservation of individual non-coding RNA elements in the 3`-UTRs. The data show novel insights into the global virus spread.