FIG 1.

Silencing SUMO E2 enzyme Ubc9 represses DENV replication. (A and B) A549 cells were transfected with the indicated siRNAs for 48 h and then infected with DENV serotype 2 (MOI of 0.1) for another 48 h. Intracellular protein expression levels and infectious DENV titer in the culture supernatant were measured by Western blotting (WB) (A) and by plaque forming assay (B), respectively. Data are expressed as means and standard deviations (SD) (n = 3 per group) and were compared to those for siCtrl by two-tailed Student's t test. (C and D) A stable BHK-21 cell line harboring DENV2 replicon were transfected with the indicated siRNAs for 48 h. WB (C) and luciferase assay (D) were carried out to analyze the indicated protein expression levels and the replication levels of DENV2 replicon. (E and F) A549 cells stably expressing shRNA targeting control LacZ or Ubc9 were infected with DENV (MOI, 0.1 and 10) for 24 h. Cell lysates were analyzed by WB with the indicated antibodies (E), and culture supernatants were harvested for virus titration by performing plaque assays (F). The error bars represent the means and SD (n = 3 per group) and were compared by Student's t test.