Efficacy of Bidens pilosa Extract against Herpes Simplex Virus Infection In Vitro and In Vivo
Time of addition studies. (a) Mode of inhibitory effect of B. pilosa extract against HSV-2 during different periods of the viral replication cycle. Vero cells were treated with 500, 1000, and 2000 μg/mL B. pilosa extract. The extract was added prior to infection (−3 h), during adsorption (0 h), or after infection (1, 2, 4, and 6 h). The prescription was either washed out at indicated times or continuously remained present for the entire 18 h period of infection (left panel). The antiviral activity was determined in Vero cells by the plaque reduction assay. After 18 h, the number of plaques of extract-treated cells was compared with untreated controls. Data are % of control and represent mean ± SD of triplicate cultures. (b) Vero cells were incubated with plain or extract-containing medium for 1 h before HSV-1 challenge (pretreatment), during viral adsorption for 1 h (adsorption), for 1 h to allow viral internalization into cells (penetration), and during cultivation (replication). After 72 h, the number of plaques of extract-treated cells was compared with untreated controls. Data are presented as % of control.