2.7. Plaque reduction assay

The HSV-1 plaque reduction assay was performed essentially according to CLSI guidelines (Sweirkosz, 2004). HSV-1 virus was added to 90% confluent Vero cell monolayers in 6-well plates at a titer of ≈250 plaque forming units (PFU)/well. After incubation for 1h, the inoculum was removed and DMEM supplemented with 0.5% carboxymethylcellulose and the indicated concentrations (serial 2-fold dilutions from 10,000-19.5ng/ml) of peg-ArgI was added. After 72h incubation, the number of viral plaques was determined by counting visually under high powered magnification. Any focal point of CPE no matter the size was counted as a plaque. The percentage of inhibition for each treatment condition was determined relative to the average number of plaques in the mock treated controls. Results were log transformed and analyzed in GraphPad by nonlinear regression using the program’s inhibitor response analysis package. The concentration of drug that inhibited a given percentage of the plaque formation in each well (% Inhibitory Concentration; IC_x%), as well as the 95% confidence intervals for each IC was determined using the software’s inhibitory dose response analysis package.