Fig. 5.

Diphyllin inhibited virus replication of H6N1 avian influenza virus and dengue virus serotype 2. (A) MDCK cells were pretreated with diphyllin 1 h prior to strain A/Duck/Yilan/2904/99(H6N1) infection at an MOI of 0.1. Infected cells without diphyllin treatment were used as controls (black bars). After a 1-h period of infection, cells were washed, overlaid with fresh media containing the same concentrations of diphyllin as in previous step, and incubated for another 40 h. The cell culture supernatant was harvested for TCID₅₀ assay (left) and HA test (right), respectively. (B) A549 cells were treated with diphyllin using the same procedures as above, and the DENV2 was inoculated for infection (MOI = 0.01). Twenty-four hours later, the culture supernatant and cells were harvested to determine the virus titers using plaque assay (left) and real-time quantitative RT-PCR (right), respectively. Values are mean ± SD from three replicates. Viral titers between each treated group and the untreated control group were compared by one-way ANOVA followed by Dunnett’s multiple comparisons test. (ns: non-significant, ^∗p < 0.05, ^∗∗p < 0.01, ^∗∗∗p < 0.001, ^∗∗∗∗p < 0.0001).