Endogenous miR-484 and miR-744 expression is downregulated by the DENV 3′ UTR - It is reported that sfRNA derived from the DENV 3′ UTR is abundantly expressed during infection by all flaviviruses in cultured cells (Lin et al. 2004) and functions as an RNAi suppressor during flavivirus replication; sfRNA has also been shown to interfere in vitro with the processing of the double-stranded RNA (dsRNA) template by Dicer (Schnettler et al. 2012). Because DENV infection downregulates miR-484 and miR-744 expression in Vero cells, we examined whether the DENV 3′ UTR is involved in this process. Thus, Vero cells were transfected with the pGUD1, pGUD2, or pGUD4 constructs, with the pEGFP-C1 empty vector serving as control. The effect of the 3′ UTR on endogenous miR-484 and miR-744 expression was examined at 12, 24, 48, and 72 h post-transfection (hpt) by RT-qPCR, and for the analysis, each time-point was compared with the control (pEGFP-C1) and the levels of significance were determined (*p < 0.05). As shown in Fig. 5A, the 3′ UTR of DENV-1 RNA (pGUD1), DENV-2 RNA (pGUD2), and DENV-4 RNA (pGUD4) induced a greater than 2-fold change, which is statistically significant, in the expression of miR-484, at all-time-points evaluated, except for DENV-2 at 48 hpt (Fig. 5A). Similar results were obtained for miR-744 (Fig. 5B), but since the observed fold change was less pronounced than that with miR-484, possibly because we used the human miR-744 with the model Vero cells of monkey origin. Thus, we wondered if miR-744 and miR-484 are conserved in humans and monkeys. Firstly, to answer this question, we amplified both miR-484 and miR-744 in HeLa cells and Vero cells, by RT-qPCR using the same probe and observed that both miR-484 and miR-744 were amplified (data not shown). Although this finding does not explain the results in Figs 2B and 5B, it allows us to suggest that the nucleotide sequences of these two miRNAs are possibly conserved between monkeys and humans. Interestingly, the 3′ UTR of DENV-1 RNA induced the strongest decrease in miR-484 and miR-744 expression at 24 hpi (Fig. 5A-B).