Abstract
Plaque assay was performed on herpes simplex type 1, using Vero, BHK-21, Hep-2 and LLCMK2 cell lines. The plaquing efficiency was optimal when 60 mm dishes containing Vero cells received an inoculum of 200 microliters with an adsorption time of 90 min. The overlay contained agar and tissue culture medium supplemented with extra vitamins, DEAE-Dextran and magnesium chloride. Virus titer was increased by two fold and plaques were clearly visible within three days of incubation. This modified method was reproducible and is being used routinely in our research and diagnostic laboratories.