Engineered CVB3-miRTs exhibit attenuated replication kinetics due to endogenous miR-206– and miR-133–mediated repression. (A) Replication kinetics of CVB3-WT, CVB-206T, CVB-3*T, and CVB-CON in HeLa cells, which express low levels of either miR-206 or miR-133. Virus titer values represent the means ± the standard deviations (SD) of three independent experiments. CVB-206T (B) and CVB-3*T (C) virus in the supernatants of HeLa cells after four passages were sequenced. (D) Replication kinetics of CVB-206T, CVB-3*T, CVB3-WT, and CVB-CON in TE671 cells that had high levels of endogenous miR-206 expression. Virus titer values represent the means ± the SD of three independent experiments. (E) TE671 cell viability in cells infected with the CVB-miRTs compared to cells infected with the control viruses, as determined by MTS assay. (F) Virus titers of CVB3-miRTs and CVB-CON in L6 cells that express a high level of endogenous miR-206. Virus titer values represent the means ± the SD of three independent experiments. (G) L6 cell viability in cells at 72 h postinfection with the CVB-miRTs compared to cells infected with the control viruses, as determined by MTS assay. (H) Virus titers of CVB3-miRTs and CVB-CON in HeLa cells transfected with miR-133 and/or miR-206 mimics 4 h before infection. (I) HeLa cell viability in cells transfected with miR-133 and/or miR-206 mimics. *, P < 0.01 for the CVB-206T and CVB-3*T groups compared to the CVB-CON group. Values represent the means ± the SD.