In order to support these findings, more physiological relevant studies were performed by analyzing the effect of resveratrol on KSHV-infected cells. Resveratrol, or trans-3,5,49-trihydroxystilbene, is a phytoalexin that is produced in various plants such as grapes, berries, and peanuts in response to attacks by pathogens [14] . Several reports provide evidence for resveratrol to exhibit antiviral effects [27, 34, 35] . On the other hand, resveratrol has also been shown to induce virus replication [36, 37] . We have demonstrated that resveratrol, in its chemical form, inhibits 1-3) were incubated at 37uC for 48 h while the cells transfected with egr-1/pcDNA3.1 were incubated for 24, 48, and 72 h, respectively. At the end of incubation, the cells were lysed and the lysates were used to perform Western blotting. (B) Effect of elevated Egr-1 on KSHV ORF50 and ORF8 expression. BCBL-1 cells were untransfected or transfected as described above. RNA was extracted, cDNA was synthesized, and the expression of cellular egr-1; and KSHV encoded ORF50 and ORF8 were analyzed by qRT-PCR. Baseline expression of genes was considered as 1-fold for comparisons. Each point denotes the average6S.D. (error bars) of three experiments. (C) Expression of lytic proteins in BCBL-1 cells transfected with Egr-1. KSHV-infected cells were untransfected, transfected with pcDNA3.1, or egr-1/pcDNA3.1 for 48 h. The stained cells examined using a confocal microscope (magnification 662). The average number of fluorescent cells were counted over five random fields and used for comparisons. (D) Enhanced egr-1 activates MAPK signaling in BCBL-1 cells. KSHV-infected cells were untransfected, mock-transfected, transfected with pcDNA3.1(+), or egr-1/pcDNA3.1(+) for 48 h. Each group of cells was left untreated or they were treated with 10 mM of U0126 1 h prior to transfection and remained throughout the incubation period. Cell lysates were resolved on a 10% SDS-PAGE, transferred to a PVDF membrane, and Western blotting was performed using specific antibodies. (E) U0126 inhibits phosho-ERK1/2 and Egr-1. Briefly, BCBL-1 cells were treated with different concentrations of U0126. Following 24 h incubation, the cells were lysed and the lysates were used to perform Western blotting as per earlier protocols using specific antibodies. doi:10.1371/journal.pone.0033364.g004 Egr-1 and phospho-ERK1/2 in KSHV-infected cells (Fig. 5B) . RDS significantly inhibited KSHV reactivation in uninduced and TPA-induced cells (Fig. 6A , B, C, D). While performing these experiments we noticed that unfiltered RDS was able to inhibit KSHV reactivation to a greater extent when compared to cells treated with RDS that was passed through a 0.2 mm filter. However, both treatments were able to significantly inhibit gene products associated with KSHV reactivation (Fig. 6A, D) . These differences are likely due to the presence of unknown factors in unfiltered RDS that may act in combination with resveratrol. Incidentally, the decrease in the expression of RTA by RDS coincided with a sharp decline in the ability of Egr-1 to bind ORF50P as shown by the semi-quantitative ChIP assay (Fig. 6E) . Taken together, this is the first report to describe the role of physiologically relevant RDS on KSHV infection.