Figure 4.

Evaluation of antiviral activities of CHLA and PUG that affect virus attachment and penetration. (A) Schematics of the experiments with the virus concentration (PFU/well or MOI) and the time of addition and treatment with tannins (i, ii, iii) for each virus in the associated tables. In virus attachment analysis by Method 1 (light gray bars), monolayers of different cell types were pre-chilled at 4°C for 1 h, and then co-treated with the respective viruses and test compounds at 4°C (1.5 – 3 h; i) before washing off the inoculates and test compounds for subsequent incubation (37°C; ii) and examination of virus infection. In virus penetration analysis (dark gray bars), seeded cell monolayers were pre-chilled at 4°C for 1 h and then challenged with the respective viruses at 4°C for 1.5 – 3 h (i). Cells were then washed and treated with the test compounds for an additional incubation period (ii) during which the temperature was shifted to 37°C to facilitate viral penetration. At the end of the incubation, extracellular viruses were removed by either citrate buffer (pH 3.0) or PBS washes and the cells were further incubated (iii) for analysis of virus infection. Results for (B) HCMV, (C) HCV, (D) DENV-2, (E) MV, and (F) RSV are indicated in each additional panel. Data are plotted against the DMSO negative control treatment of virus infection and are presented as means ± SEM from three independent experiments. See text for details.