The analysis of virus inactivation VERO cells infected with HSV-1 were added with 20 µL (5 mg/mL) of MTT to each well and incubated at 37°C for 4 hours. Then, 150 µL of DMSO was added to each well. The OD 490 was read by a microplate spectrophotometer. The percentage of inhibition was calculated by the formula described under the heading "Measurement of cytotoxicity."