Fig. 2.

Luciferase-based viral yield and cytotoxicity assays. (A) Antiviral activity of emodin (blue line) was determined by infecting confluent MRC-5 monolayers in 96-well plates with luciferase-tagged CMV RC2626 at an MOI of 0.03 in the presence of increasing concentrations emodin. After 5 days supernatants were transferred to 96-well plates containing fresh MRC-5 monolayers and 24 h later the cultures were lysed and luciferase activities determined as a measure of virus in the transferred culture supernatants. Cytotoxicity (red line) was determined by incubating replicate uninfected cultures with emodin for 5 days, then determining luciferase activities as a measure of cell viability using the CellTiter-Glo assay. (B) Antiviral activities of the indicated compounds were determined as described for panel A. (C) Cytotoxicities of the indicated compounds were determined as described for panel A. (D) Results from panels B and C are graphed together to illustrate the difference between antiviral activity (blue) and cytotoxicity (red) of atanyl blue PRL. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)