Research Article

A Laboratory Evaluation of Medicinal Herbs Used in China for the Treatment of Hand, Foot, and Mouth Disease

Figure 1

Antiviral activity evaluation of HCT and MHB extracts against EV71 and CVA16. (a, b) Pretreatment of Vero cells with HCT or MHB blocks the cytopathic effect by virus infection. Vero cells were pretreated with or without a herb extract at concentrations as indicated for 2 hr, and the cells were then infected with EV71 (a, Fuyang strain) or CVA16 (b) at an MOI of 0.2 TCID50/cell or PFU/cell. After incubation for 72 hr, the cells were fixed with 3% formaldehyde, stained with 0.5% crystal violet. The cells were photographed. To quantitatively measure the staining, crystal violet was extracted by DMSO, and the absorbance at 570 nm was measured colorimetrically. An increase in reading compared with that of an infected control indicates an inhibitory effect of the extract against virus infection. Data are presented as mean ± SE of duplicate samples. (c, d) HCT and MHB treatments reduce infectious virion production of EV71 and CVA16, respectively. Vero cells were infected with EV71 or CVA16 (MOI = 0.2) in the presence or absence of a herbal extract at indicated concentrations. The cells and culture supernatants were harvested at 48 hr PI and determined for virus titration by TCID50 assay for EV71 (c) and by plaque forming assay for CVA16 (d). Data are presented as mean ± SE of triplicate samples. The results are representative of two independent experiments.