Elsevier

Virus Research

Volume 206, 3 August 2015, Pages 99-107
Virus Research

The 5′ and 3′ ends of alphavirus RNAs – Non-coding is not non-functional

https://doi.org/10.1016/j.virusres.2015.01.016Get rights and content

Highlights

  • Evolution of the CHIKV 3′ UTR is shaped by fitness concerns in different hosts.

  • The 5′ UTR can antagonize host innate immune defenses.

  • 3′ UTR interactions with miRNAs determine cellular tropism and disease pathogenesis.

  • Viral RNA stability is mediated by cellular HuR protein interaction with the 3′ UTR.

Abstract

The non-coding regions found at the 5′ and 3′ ends of alphavirus genomes regulate viral gene expression, replication, translation and virus–host interactions, which have significant implications for viral evolution, host range, and pathogenesis. The functions of these non-coding regions are mediated by a combination of linear sequence and structural elements. The capped 5′ untranslated region (UTR) contains promoter elements, translational regulatory sequences that modulate dependence on cellular translation factors, and structures that help to avoid innate immune defenses. The polyadenylated 3′ UTR contains highly conserved sequence elements for viral replication, binding sites for cellular miRNAs that determine cell tropism, host range, and pathogenesis, and conserved binding regions for a cellular protein that influences viral RNA stability. Nonetheless, there are additional conserved elements in non-coding regions of the virus (e.g., the repeated sequence elements in the 3′ UTR) whose function remains obscure. Thus, key questions remain as to the function of these short yet influential untranslated segments of alphavirus RNAs.

Keywords

Translation regulation
Polyadenylation
mRNA capping
Viral pathogenesis
miRNAs
Protein–RNA interactions

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1

These authors contributed equally to the manuscript.

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