Direct inactivation of essential oils from Colombian plants on yellow fever virus (YFV). About 9.5 × 104 PFU of YFV were incubated for 24 h at 4°C with concentrations of essential oil and then were adsorbed on Vero cells. Virus titers in supernatants of cell cultures were determined by plaque assays method at 48 h after adsorption. The data represent the means for three replicate samples of two independent experiment. Error bars indicate standard deviations.