Fig. 1.

Inhibition of herpes simplex virus-2 infection by Houttuynia cordata water extract. Dose response of HCWE on HSV-2 infection. (A) Monolayers of Vero cells in 96-well plates were infected with HSV-2 at an MOI of 2 in the presence or absence of HCWE at 45, 150, 450 μg/ml. HSV-2 infection caused cytolytic effect. At 48 h PI, cells that remained attached were quantitatively measured for their activity to reduce MTT to formazan. An increased reading from MTT assay indicates reduction of virus infection. Acyclovir (ACV) at 5 μM was used as a positive control against virus infection. Data are representative of 3 independent experiments of triplicate samples. (B) In parallel experiments, culture supernatants were collected and assayed for production of infectious virus by plaque forming assay. Data are presented as mean ± standard deviation of triplicate samples. ^∗P < 0.05, ^∗∗P < 0.01 compared with HSV-2 samples determined by ANOVA. (C) Time course of HCWE treatment on HSV-2 infection. HCWE at 450 μg/ml was added at 2 h prior to (-2 h), during (0 h), or at indicated times post virus inoculation (2, 6, and 12 h PI). Inhibition of virus infection was determined by using MTT assay. The data are presented as mean ± standard deviation of triplicate samples, and the results represent three independent experiments. No significant difference on HSV-2 infection was detected when HCWE was added 2 h prior to or within 6 h post inoculation.