FIG 2.

miR-21 attenuates HCMV replication in U-251MG cells. (A) U-251MG cells were transduced at an MOI of 10 with lentiviruses expressing miR-21 (21) or a control miRNA, miR-UL22A (Ctrl).Cellular morphology was monitored by phase-contrast microscopy, and the transduction efficiency was determined by the detection of lentivirus-encoded GFP at 48 hpt (left). The miR-21 levels at 48 hpt were quantified by qRT-PCR and expressed as fold differences relative to Ctrl (right). (B) Transduced U-251MG cells were infected with HCMV at an MOI of 1, and viral and cellular proteins were detected by Western blotting at the indicated times postinfection. Protein levels relative to Ctrl were determined by densitometry and are indicated below each blot. Actin serves as a loading control. (C) HCMV DNA copy number per cell was determined by qRT-PCR and standardized to cellular DNA (GAPDH) copy number. (D) Titers of infectious virus in the culture supernatants at 72 and 96 hpi were determined by plaque assay. The fold differences are indicated. miR-21, HCMV genome copy number, and virus titer results are means ± 1 SD of data from three independent experiments, each conducted in triplicate. *, P < 0.05; **, P < 0.01.