Translational Regulation by the 3′ Untranslated Region of the Dengue Type 2 Virus Genome

The role of the 3′untranslated region (UTR) of the dengue virus (DENV) genome during viral translation remains to be elucidated. We assessed the contribution of well-defined RNA elements in the 3′UTR of DENV-2 to viral translation using a virus-induced reporting gene system and deoxyribozymes (DRzs) targeting the 3′UTR of the DENV-2 genome. Results show that mRNAs carrying a deletion of repeated conserved sequence (RCS2)-CS2 are translated less efficiently than wild type mRNAs. However, mRNAs with a deletion of CS1-stem loop (SL) are translated more efficiently. Thus, CS1-SL and RCS2-CS2 may have different effects on translational regulation. Additionally, the translation-suppressing effect of CS1-SL or the SL element is further confirmed in DENV-2-infected cells using DRzs. Mutagenesis studies show that, rather than the secondary structure, nucleotides 10663–10677 and 10709–10723 are responsible for translational suppression of SL. Overall, our results demonstrate that sequences and elements within the DENV-2 3′UTR regulate viral translation.